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<!-- Weave of 'Architecture of the S - Parser' generated by Inweb -->
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< ul class = "crumbs" > < li > < a href = "../index.html" > Home< / a > < / li > < li > < a href = "../compiler.html" > Inform7< / a > < / li > < li > < a href = "index.html" > values< / a > < / li > < li > < a href = "index.html#4" > Chapter 4: The S-Parser< / a > < / li > < li > < b > Architecture of the S-Parser< / b > < / li > < / ul > < / div >
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< p class = "purpose" > Top-level structure of the S-parser, which turns text into S-nodes.< / p >
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< ul class = "toc" > < li > < a href = "4-aots.html#SP1" > § 1. Introduction< / a > < / li > < li > < a href = "4-aots.html#SP3" > § 3. Top-level nonterminals< / a > < / li > < li > < a href = "4-aots.html#SP11" > § 11. The cache< / a > < / li > < li > < a href = "4-aots.html#SP15" > § 15. Void phrases< / a > < / li > < / ul > < hr class = "tocbar" >
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< p class = "commentary firstcommentary" > < a id = "SP1" class = "paragraph-anchor" > < / a > < b > § 1. Introduction. < / b > The purpose of the S-parser is to turn excerpts of text into specification
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nodes. Nonterminals here almost all have names beginning with the "s-" prefix,
which indicates that their results are S-nodes.
< / p >
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< p class = "commentary" > The simplest nonterminal in the S-grammar is < s-plain-text> , which
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accepts any non-empty piece of text. (The same can be said exactly of
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< np-unparsed> , and the difference is purely to do with how Inform stores
the results: < np-unparsed> makes nodes in the main parse tree, a rather
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permanent structure, whereas < s-plain-text> makes an S-node.)
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-plain-text> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
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< span class = "Preform-plain-syntax" > ==> { -, < / span > < a href = "2-spc.html#SP10" class = "function-link" > < span class = "Preform-function-syntax" > Specifications::new_UNKNOWN< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > ) };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP2" class = "paragraph-anchor" > < / a > < b > § 2. < / b > And here is a curious variation, which is needed because equations are
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parsed with completely different spacing rules, and don't respect words. It
matches any non-empty text where one of the words contains an equals sign
as one of its characters: thus
< / p >
< blockquote >
< p > V = fl< / p >
< / blockquote >
< blockquote >
< p > F=ma< / p >
< / blockquote >
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< p class = "commentary" > both match this, the first example being three words long, the second only one.
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< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-plain-text-with-equals> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > LOOP_THROUGH_WORDING< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > i< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > ) {< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > wchar_t< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > Lexer::word_raw_text< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > i< / span > < span class = "Preform-plain-syntax" > );< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > for< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > j< / span > < span class = "Preform-plain-syntax" > =0; < / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > [< / span > < span class = "Preform-identifier-syntax" > j< / span > < span class = "Preform-plain-syntax" > ]; < / span > < span class = "Preform-identifier-syntax" > j< / span > < span class = "Preform-plain-syntax" > ++)< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > [< / span > < span class = "Preform-identifier-syntax" > j< / span > < span class = "Preform-plain-syntax" > ] == < / span > < span class = "Preform-character-syntax" > '='< / span > < span class = "Preform-plain-syntax" > ) {< / span >
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< span class = "Preform-plain-syntax" > ==> { -, < / span > < a href = "2-spc.html#SP10" class = "function-link" > < span class = "Preform-function-syntax" > Specifications::new_UNKNOWN< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > ) };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< span class = "Preform-plain-syntax" > ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP3" class = "paragraph-anchor" > < / a > < b > § 3. Top-level nonterminals. < / b > These five nonterminals are the most useful and powerful, so they're the
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main junction between the S-parser and the rest of Inform.
< / p >
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< p class = "commentary" > These are coded as internals for efficiency's sake. We will often reparse the
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same wording over and over, so we cache the results. But < s-value> matches
exactly the same text as < s-value-uncached> , and so on for the other four.
< / p >
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< p class = "commentary" > < s-value> looks for source text which can be evaluated — a constant, a
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variable or other storage object, or a phrase to decide a value.
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-value> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > = < / span > < a href = "4-aots.html#SP13" class = "function-link" > < span class = "Preform-function-syntax" > ExParser::parse_with_cache< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-constant-syntax" > 0< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-function-syntax" > < s-value-uncached> < / span > < span class = "Preform-plain-syntax" > );< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > Node::is< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > UNKNOWN_NT< / span > < span class = "Preform-plain-syntax" > )) { ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > }; }< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP4" class = "paragraph-anchor" > < / a > < b > § 4. < / b > < s-condition> looks for a condition — anything legal after an
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"if", in short. This includes sentence-like excerpts such as "six
animals have been in the Stables".
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-condition> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > LocalVariables::make_necessary_callings< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > );< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > = < / span > < a href = "4-aots.html#SP13" class = "function-link" > < span class = "Preform-function-syntax" > ExParser::parse_with_cache< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-constant-syntax" > 1< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-function-syntax" > < s-condition-uncached> < / span > < span class = "Preform-plain-syntax" > );< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > Node::is< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > UNKNOWN_NT< / span > < span class = "Preform-plain-syntax" > )) { ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > }; }< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP5" class = "paragraph-anchor" > < / a > < b > § 5. < / b > < s-non-action-condition> is the same, but disallowing action patterns
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as conditions, so for example "taking something" would not match.
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-non-action-condition> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > LocalVariables::make_necessary_callings< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > );< / span >
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< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > ifdef< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > IF_MODULE< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > old_state< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > PL::Actions::Patterns::suppress< / span > < span class = "Preform-plain-syntax" > ();< / span >
< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > endif< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > = < / span > < a href = "4-aots.html#SP13" class = "function-link" > < span class = "Preform-function-syntax" > ExParser::parse_with_cache< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-constant-syntax" > 2< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-function-syntax" > < s-condition-uncached> < / span > < span class = "Preform-plain-syntax" > );< / span >
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< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > ifdef< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > IF_MODULE< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > PL::Actions::Patterns::resume< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > old_state< / span > < span class = "Preform-plain-syntax" > );< / span >
< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > endif< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > Node::is< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > UNKNOWN_NT< / span > < span class = "Preform-plain-syntax" > )) { ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > }; }< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP6" class = "paragraph-anchor" > < / a > < b > § 6. < / b > < s-type-expression> is for where we expect to find the "type" of something
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— for instance, the kind of value to be stored in a variable, or the
specification of a phrase argument.
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-type-expression> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > = < / span > < a href = "4-aots.html#SP13" class = "function-link" > < span class = "Preform-function-syntax" > ExParser::parse_with_cache< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-constant-syntax" > 3< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-function-syntax" > < s-type-expression-uncached> < / span > < span class = "Preform-plain-syntax" > );< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > Node::is< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > UNKNOWN_NT< / span > < span class = "Preform-plain-syntax" > )) { ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > }; }< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP7" class = "paragraph-anchor" > < / a > < b > § 7. < / b > < s-descriptive-type-expression> is the same thing, with one difference: it
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allows nounless descriptions, such as "open opaque fixed in place", and to
this end it treats bare adjective names as descriptions rather than values. If
we have said "Colour is a kind of value. The colours are red, green and taupe.
A thing has a colour.", then "green" is parsed by < s-descriptive-type-expression>
as a description meaning "any thing which is green", but by < s-type-expression>
and < s-value> as a constant value of the kind "colour".
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-descriptive-type-expression> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > = < / span > < a href = "4-aots.html#SP13" class = "function-link" > < span class = "Preform-function-syntax" > ExParser::parse_with_cache< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-constant-syntax" > 4< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-function-syntax" > < s-descriptive-type-expression-uncached> < / span > < span class = "Preform-plain-syntax" > );< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > Node::is< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > UNKNOWN_NT< / span > < span class = "Preform-plain-syntax" > )) { ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > }; }< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > spec< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP8" class = "paragraph-anchor" > < / a > < b > § 8. < / b > The following internal is just a shell for < s-descriptive-type-expression> ,
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but it temporarily changes the parsing mode to phrase token parsing, so that
kind variables will be read as formal prototypes.
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-phrase-token-type> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > s< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > kind_parsing_mode< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > kind_parsing_mode< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > PHRASE_TOKEN_KIND_PARSING< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > t< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-function-syntax" > < s-descriptive-type-expression> < / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > );< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > kind_parsing_mode< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > s< / span > < span class = "Preform-plain-syntax" > ;< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > t< / span > < span class = "Preform-plain-syntax" > ) { ==> { < / span > < span class = "Preform-function-syntax" > < < r> > < / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-function-syntax" > < < rp> > < / span > < span class = "Preform-plain-syntax" > }; < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ; }< / span >
< span class = "Preform-plain-syntax" > ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP9" class = "paragraph-anchor" > < / a > < b > § 9. < / b > That's it for the cached nonterminals, but we will also define a convenient
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super-nonterminal which matches almost any meaningful reference to data, so
it's frequently used as a way of finding out whether a new name will clash
with some existing meaning.
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-type-expression-or-value> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > ::=< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-function-syntax" > < s-type-expression> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > |< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > ==> < / span > < span class = "Preform-plain-syntax" > { pass 1 }< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-function-syntax" > < s-value> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > ==> < / span > < span class = "Preform-plain-syntax" > { pass 1 }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP10" class = "paragraph-anchor" > < / a > < b > § 10. < / b > One further convenience is for text which describes an explicit action in
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a noun-like way.
< / p >
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< pre class = "Preform-displayed-code all-displayed-code code-font" >
< span class = "Preform-function-syntax" > < s-explicit-action> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > ifdef< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > IF_MODULE< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > NULL< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > permit_trying_omission< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > permit_trying_omission< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-function-syntax" > < s-condition-uncached> < / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > )) < / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-function-syntax" > < < rp> > < / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > permit_trying_omission< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > ) {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < a href = "2-rvl.html#SP21" class = "function-link" > < span class = "Preform-function-syntax" > Rvalues::is_CONSTANT_of_kind< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > K_stored_action< / span > < span class = "Preform-plain-syntax" > )) {< / span >
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< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > };< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
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< span class = "Preform-plain-syntax" > } < / span > < span class = "Preform-reserved-syntax" > else< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < a href = "2-cnd.html#SP10" class = "function-link" > < span class = "Preform-function-syntax" > Conditions::is_TEST_ACTION< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > )) {< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > -> < / span > < span class = "Preform-identifier-syntax" > down< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
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< span class = "Preform-plain-syntax" > } < / span > < span class = "Preform-reserved-syntax" > else< / span > < span class = "Preform-plain-syntax" > {< / span >
< span class = "Preform-plain-syntax" > ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > };< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< span class = "Preform-plain-syntax" > }< / span >
< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > endif< / span >
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< span class = "Preform-plain-syntax" > ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > }< / span >
< span class = "Preform-function-syntax" > < s-constant-action> < / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > internal< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > {< / span >
< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > ifdef< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > IF_MODULE< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > parse_node< / span > < span class = "Preform-plain-syntax" > *< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > NULL< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > permit_trying_omission< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > permit_trying_omission< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > int< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > p2< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > permit_nonconstant_action_parameters< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > permit_nonconstant_action_parameters< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > FALSE< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-function-syntax" > < s-condition-uncached> < / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > W< / span > < span class = "Preform-plain-syntax" > )) < / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-function-syntax" > < < rp> > < / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > permit_trying_omission< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > p< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > permit_nonconstant_action_parameters< / span > < span class = "Preform-plain-syntax" > = < / span > < span class = "Preform-identifier-syntax" > p2< / span > < span class = "Preform-plain-syntax" > ;< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > ) {< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < a href = "2-rvl.html#SP21" class = "function-link" > < span class = "Preform-function-syntax" > Rvalues::is_CONSTANT_of_kind< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > , < / span > < span class = "Preform-identifier-syntax" > K_stored_action< / span > < span class = "Preform-plain-syntax" > )) {< / span >
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< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > };< / span >
< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
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< span class = "Preform-plain-syntax" > } < / span > < span class = "Preform-reserved-syntax" > else< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > if< / span > < span class = "Preform-plain-syntax" > (< / span > < a href = "2-cnd.html#SP10" class = "function-link" > < span class = "Preform-function-syntax" > Conditions::is_TEST_ACTION< / span > < / a > < span class = "Preform-plain-syntax" > (< / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > )) {< / span >
< span class = "Preform-plain-syntax" > ==> { -, < / span > < span class = "Preform-identifier-syntax" > S< / span > < span class = "Preform-plain-syntax" > -> < / span > < span class = "Preform-identifier-syntax" > down< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > < / span > < span class = "Preform-reserved-syntax" > return< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > TRUE< / span > < span class = "Preform-plain-syntax" > ;< / span >
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< span class = "Preform-plain-syntax" > } < / span > < span class = "Preform-reserved-syntax" > else< / span > < span class = "Preform-plain-syntax" > {< / span >
< span class = "Preform-plain-syntax" > ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > };< / span >
< span class = "Preform-plain-syntax" > }< / span >
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< span class = "Preform-plain-syntax" > }< / span >
< span class = "Preform-plain-syntax" > #< / span > < span class = "Preform-identifier-syntax" > endif< / span >
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< span class = "Preform-plain-syntax" > ==> { < / span > < span class = "Preform-identifier-syntax" > fail< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-identifier-syntax" > nonterminal< / span > < span class = "Preform-plain-syntax" > };< / span >
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< span class = "Preform-plain-syntax" > }< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This is < a href = "../words-module/4-ap.html" class = "internal" > Preform grammar< / a > , not regular C code.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP11" class = "paragraph-anchor" > < / a > < b > § 11. The cache. < / b > The above nonterminals are called pretty frequently on overlapping or
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coinciding runs of text. Inform runs substantially faster if the results of
parsing the most recent expressions are cached; so, for instance, if Inform
parses the text in words 507 to 511 once, it need not do so again in the same
context.
< / p >
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< p class = "commentary firstcommentary" > < a id = "SP12" class = "paragraph-anchor" > < / a > < b > § 12. < / b > The cache takes the form of a modest ring buffer for each of the contexts:
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< / p >
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< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "Preform-constant-syntax" > MAXIMUM_CACHE_SIZE< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > 20< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-comment-syntax" > a Goldilocks value: too high slows us down, too low doesn't cache enough< / span >
< span class = "definition-keyword" > define< / span > < span class = "Preform-constant-syntax" > NUMBER_OF_CACHED_NONTERMINALS< / span > < span class = "Preform-plain-syntax" > < / span > < span class = "Preform-constant-syntax" > 5< / span >
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< / pre >
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< pre class = "displayed-code all-displayed-code code-font" >
< span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > expression_cache< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > expression_cache_entry< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > pe_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "constant-syntax" > MAXIMUM_CACHE_SIZE< / span > < span class = "plain-syntax" > ];< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > pe_cache_size< / span > < span class = "plain-syntax" > ; < / span > < span class = "comment-syntax" > number of entries used, 0 to < / span > < span class = "extract" > < span class = "extract-syntax" > MAXIMUM_CACHE_SIZE< / span > < / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > ; < / span > < span class = "comment-syntax" > next write position, 0 to < / span > < span class = "extract" > < span class = "extract-syntax" > pe_cache_size< / span > < / span > < span class = "comment-syntax" > minus 1< / span >
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > expression_cache< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > expression_cache_entry< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > wording< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > cached_query< / span > < span class = "plain-syntax" > ; < / span > < span class = "comment-syntax" > the word range whose parsing this is< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > cached_result< / span > < span class = "plain-syntax" > ; < / span > < span class = "comment-syntax" > and the result (quite possibly < / span > < span class = "extract" > < span class = "extract-syntax" > UNKNOWN_NT< / span > < / span > < span class = "comment-syntax" > )< / span >
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > expression_cache_entry< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > expression_cache_has_been_used< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > FALSE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > expression_cache< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > contextual_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "constant-syntax" > NUMBER_OF_CACHED_NONTERMINALS< / span > < span class = "plain-syntax" > ];< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > The structure expression_cache is private to this section.< / li > < li > The structure expression_cache_entry is private to this section.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP13" class = "paragraph-anchor" > < / a > < b > § 13. < / b > < / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > ExParser::parse_with_cache< / span > < button class = "popup" onclick = "togglePopup('usagePopup1')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup1" > Usage of < span class = "code-font" > < span class = "function-syntax" > ExParser::parse_with_cache< / span > < / span > :< br / > < a href = "4-aots.html#SP3" > § 3< / a > , < a href = "4-aots.html#SP4" > § 4< / a > , < a href = "4-aots.html#SP5" > § 5< / a > , < a href = "4-aots.html#SP6" > § 6< / a > , < a href = "4-aots.html#SP7" > § 7< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > wording< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > context< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > nonterminal< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nt< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Wordings::empty< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > )) < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "2-spc.html#SP10" class = "function-link" > < span class = "function-syntax" > Specifications::new_UNKNOWN< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > context< / span > < span class = "plain-syntax" > < < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ) || (< / span > < span class = "identifier-syntax" > context< / span > < span class = "plain-syntax" > > = < / span > < span class = "constant-syntax" > NUMBER_OF_CACHED_NONTERMINALS< / span > < span class = "plain-syntax" > ))< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "bad expression parsing context"< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "named-paragraph-container code-font" > < a href = "4-aots.html#SP13_1" class = "named-paragraph-link" > < span class = "named-paragraph" > Check the expression cache to see if we already know the answer< / span > < span class = "named-paragraph-number" > 13.1< / span > < / a > < / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > unwanted< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > plm< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > preform_lookahead_mode< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > preform_lookahead_mode< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > FALSE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Preform::parse_nt_against_word_range< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nt< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > , & < / span > < span class = "identifier-syntax" > unwanted< / span > < span class = "plain-syntax" > , (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > **) & < / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > )) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Wordings::empty< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > ))) < / span > < span class = "identifier-syntax" > Node::set_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > else< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > = < / span > < a href = "2-spc.html#SP10" class = "function-link" > < span class = "function-syntax" > Specifications::new_UNKNOWN< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > preform_lookahead_mode< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > plm< / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "named-paragraph-container code-font" > < a href = "4-aots.html#SP13_2" class = "named-paragraph-link" > < span class = "named-paragraph" > Write the newly discovered specification to the cache for future use< / span > < span class = "named-paragraph-number" > 13.2< / span > < / a > < / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > VerifyTree::verify_structure_from< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP13_1" class = "paragraph-anchor" > < / a > < b > § 13.1. < / b > The following seeks a previously cached answer:
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< / p >
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< p class = "commentary" > < span class = "named-paragraph-container code-font" > < span class = "named-paragraph-defn" > Check the expression cache to see if we already know the answer< / span > < span class = "named-paragraph-number" > 13.1< / span > < / span > < span class = "comment-syntax" > =< / span >
< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > expression_cache< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > = & (< / span > < span class = "identifier-syntax" > contextual_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > context< / span > < span class = "plain-syntax" > ]);< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > expression_cache_has_been_used< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > FALSE< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < a href = "4-aots.html#SP14" class = "function-link" > < span class = "function-syntax" > ExParser::warn_expression_cache< / span > < / a > < span class = "plain-syntax" > (); < / span > < span class = "comment-syntax" > this empties all the caches< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > expression_cache_has_been_used< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > TRUE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > =0; < / span > < span class = "identifier-syntax" > i< / span > < span class = "function-syntax" > < ec-> < / span > < span class = "element-syntax" > pe_cache_size< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ++)< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Wordings::eq< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ].< / span > < span class = "element-syntax" > cached_query< / span > < span class = "plain-syntax" > ))< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ].< / span > < span class = "element-syntax" > cached_result< / span > < span class = "plain-syntax" > ;< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This code is used in < a href = "4-aots.html#SP13" > § 13< / a > .< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP13_2" class = "paragraph-anchor" > < / a > < b > § 13.2. < / b > The cache expands until it reaches < span class = "extract" > < span class = "extract-syntax" > MAXIMUM_CACHE_SIZE< / span > < / span > ; after that,
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entries are written in a position cycling through the ring. In either case
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it takes < span class = "extract" > < span class = "extract-syntax" > MAXIMUM_CACHE_SIZE< / span > < / span > further parses (not found in the cache) to
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overwrite the one we put down now.
< / p >
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< p class = "commentary" > < span class = "named-paragraph-container code-font" > < span class = "named-paragraph-defn" > Write the newly discovered specification to the cache for future use< / span > < span class = "named-paragraph-number" > 13.2< / span > < / span > < span class = "comment-syntax" > =< / span >
< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > expression_cache< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > = & (< / span > < span class = "identifier-syntax" > contextual_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > context< / span > < span class = "plain-syntax" > ]);< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > ].< / span > < span class = "element-syntax" > cached_query< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > ].< / span > < span class = "element-syntax" > cached_result< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > spec< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > ++;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_size< / span > < span class = "plain-syntax" > < < / span > < span class = "constant-syntax" > MAXIMUM_CACHE_SIZE< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_size< / span > < span class = "plain-syntax" > ++;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > == < / span > < span class = "constant-syntax" > MAXIMUM_CACHE_SIZE< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > ec< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
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< / pre >
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< ul class = "endnotetexts" > < li > This code is used in < a href = "4-aots.html#SP13" > § 13< / a > .< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP14" class = "paragraph-anchor" > < / a > < b > § 14. < / b > As with all caches, we have to be careful that the information does not fall
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out of date. There are two things which can go wrong: the S-node in the cache
might be altered, perhaps as a result of the type-checker trying to force a
round peg into a square hole; or the stock of Inform's defined names might
change, so that the same text now has to be read differently.
< / p >
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< p class = "commentary" > The first problem can't be fixed here. It's tempting to try something like
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flagging S-nodes which have been altered, and then ensuring that the
cache never serves up an altered result. But that fails for timing reasons —
by the time the S-node might be altered, pointers to it may exist
in multiple data structures already, because the cache might have served
it more than once by that time. (Not just a theoretical possibility — tests
show that this does, albeit rarely, happen.) The brute force solution is to
serve a copy of the cache entry, and thus never send out the same pointer
twice. But this more than doubles the memory required to store S-nodes,
which is unacceptable, and also slows Inform down, because allocating memory
for all those copies is laborious. We therefore just have to be very careful
about modifying S-nodes which have arisen from parsing.
< / p >
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< p class = "commentary" > The second problem is easier. We require other parts of Inform which make
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or unmake name definitions to warn us, by calling this routine. Definitions
are made and unmade relatively rarely, so the performance hit is small.
< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > ExParser::warn_expression_cache< / span > < button class = "popup" onclick = "togglePopup('usagePopup2')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup2" > Usage of < span class = "code-font" > < span class = "function-syntax" > ExParser::warn_expression_cache< / span > < / span > :< br / > < a href = "4-aots.html#SP13_1" > § 13.1< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > =0; < / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > < < / span > < span class = "constant-syntax" > NUMBER_OF_CACHED_NONTERMINALS< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ++) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > contextual_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ].< / span > < span class = "element-syntax" > pe_cache_size< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > contextual_cache< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ].< / span > < span class = "element-syntax" > pe_cache_posn< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP15" class = "paragraph-anchor" > < / a > < b > § 15. Void phrases. < / b > The S-parser is also used by the main code compiler to turn phrases into
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S-nodes, using < s-command> and < s-say-command> . These however need a
wrapper: instead of turning text into an S-node, we take text from an
existing node (in the structural parse tree for a routine), turn that
into a new S-node with an invocation list below it, then glue the list
back into the original tree but throw away the S-node head.
< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > ExParser::parse_void_phrase< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < a href = "4-aots.html#SP15" class = "function-link" > < span class = "function-syntax" > ExParser::parse_phrase_inner< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > FALSE< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > ExParser::parse_say_term< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < a href = "4-aots.html#SP15" class = "function-link" > < span class = "function-syntax" > ExParser::parse_phrase_inner< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > TRUE< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > }< / span >
< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > ExParser::parse_phrase_inner< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > as_say_term< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "no node to parse"< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > down< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Wordings::nonempty< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > ))) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > results< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > as_say_term< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > FALSE< / span > < span class = "plain-syntax" > ) & & (< / span > < span class = "function-syntax" > < s-command> < / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > )))) < / span > < span class = "identifier-syntax" > results< / span > < span class = "plain-syntax" > = < / span > < span class = "function-syntax" > < < rp> > < / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > as_say_term< / span > < span class = "plain-syntax" > ) & & (< / span > < span class = "function-syntax" > < s-say-command> < / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > )))) < / span > < span class = "identifier-syntax" > results< / span > < span class = "plain-syntax" > = < / span > < span class = "function-syntax" > < < rp> > < / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > results< / span > < span class = "plain-syntax" > ) & & (< / span > < span class = "identifier-syntax" > results< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > down< / span > < span class = "plain-syntax" > )) < / span > < span class = "identifier-syntax" > p< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > down< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > results< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > down< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > down< / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
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< nav role = "progress" > < div class = "progresscontainer" >
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< ul class = "progressbar" > < li class = "progressprev" > < a href = "4-its.html" > ❮ < / a > < / li > < li class = "progresschapter" > < a href = "P-wtmd.html" > P< / a > < / li > < li class = "progresschapter" > < a href = "1-vm.html" > 1< / a > < / li > < li class = "progresschapter" > < a href = "2-spc.html" > 2< / a > < / li > < li class = "progresschapter" > < a href = "3-lp.html" > 3< / a > < / li > < li class = "progresscurrentchapter" > 4< / li > < li class = "progresssection" > < a href = "4-its.html" > its< / a > < / li > < li class = "progresscurrent" > aots< / li > < li class = "progresssection" > < a href = "4-pl.html" > pl< / a > < / li > < li class = "progresssection" > < a href = "4-cad.html" > cad< / a > < / li > < li class = "progresssection" > < a href = "4-teav.html" > teav< / a > < / li > < li class = "progresssection" > < a href = "4-varc.html" > varc< / a > < / li > < li class = "progresssection" > < a href = "4-cap.html" > cap< / a > < / li > < li class = "progresschapter" > < a href = "5-tl.html" > 5< / a > < / li > < li class = "progresschapter" > < a href = "6-lc.html" > 6< / a > < / li > < li class = "progresschapter" > < a href = "7-eqt.html" > 7< / a > < / li > < li class = "progressnext" > < a href = "4-pl.html" > ❯ < / a > < / li > < / ul > < / div >
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< / nav > <!-- End of weave -->
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< / main >
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< / body >
< / html >
