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< ul class = "crumbs" > < li > < a href = "../index.html" > Home< / a > < / li > < li > < a href = "../inform7n.html" > Inform7< / a > < / li > < li > < a href = "index.html" > imperative< / a > < / li > < li > < a href = "index.html#3" > Chapter 3: Functions< / a > < / li > < li > < b > Local Parking< / b > < / li > < / ul > < / div >
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< p class = "purpose" > Like Free Parking in Monopoly, except that it is not free and has an overhead cost.< / p >
< p class = "commentary firstcommentary" > < a id = "SP1" class = "paragraph-anchor" > < / a > < b > § 1. < / b > This is one of several devices we employ to get around the lack of a call stack
in memory. Suppose we want the local variables in function A to be visible to
function B, which is called from A, and suppose they cannot be passed as call
parameters to B. B cannot access them using pointers to the stack frame for A,
because the call stack does not exist in memory. What to do?
< / p >
< p class = "commentary" > What we do is to stash them into a "local parking" array, make the call to B,
and then in the code for B retrieve them again. A paraphrase might look
like this:
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "plain-syntax" > void A(void) {< / span >
< span class = "plain-syntax" > int alpha = 2, beta = 3, gamma = 5;< / span >
< span class = "plain-syntax" > lp[0] = alpha;< / span >
< span class = "plain-syntax" > lp[1] = beta;< / span >
< span class = "plain-syntax" > lp[2] = gamma;< / span >
< span class = "plain-syntax" > B();< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > void B(void) {< / span >
< span class = "plain-syntax" > int alpha = lp[0];< / span >
< span class = "plain-syntax" > int beta = lp[1];< / span >
< span class = "plain-syntax" > int gamma = lp[2];< / span >
< span class = "plain-syntax" > ...< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
< p class = "commentary" > Note that B can now read, but not write, the locals from A. The scratch array
< span class = "extract" > < span class = "extract-syntax" > lp< / span > < / span > used here for storage is meaningless except for immediately before and
after the call to B, so we don't need to worry about multiple uses of local
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parking getting in each other's way.
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< / p >
< p class = "commentary firstcommentary" > < a id = "SP2" class = "paragraph-anchor" > < / a > < b > § 2. < / b > This compiles the necessary code before the call to B:
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > LocalParking::park< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > stack_frame< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lot< / 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" > NC< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > local_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > LOOP_OVER_LOCALS_IN_FRAME< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > NC< / 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" > NC< / 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" > inter_name< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > park< / span > < span class = "plain-syntax" > = < / span > < a href = "3-lp.html#SP5" class = "function-link" > < span class = "function-syntax" > LocalParking::array< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > NC< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > inter_ti< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > j< / 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" > LOOP_OVER_LOCALS_IN_FRAME< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::inv< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > SEQUENTIAL_BIP< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::down< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::inv< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > STORE_BIP< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::down< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::reference< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::down< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::inv< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > LOOKUP_BIP< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::down< / span > < span class = "plain-syntax" > ();< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::val_iname< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > K_value< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > park< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::val_number< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > j< / span > < span class = "plain-syntax" > ++);< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::up< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::up< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > inter_symbol< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lvar_s< / span > < span class = "plain-syntax" > = < / span > < a href = "3-lv.html#SP1" class = "function-link" > < span class = "function-syntax" > LocalVariables::declare< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::val_symbol< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > K_value< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > lvar_s< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::up< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > }< / span >
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< 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" > NC< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > LocalParking::park_with_private_lot< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > stack_frame< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > rule< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > R< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > marker< / 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" > NC< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > local_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > LOOP_OVER_LOCALS_IN_FRAME< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > NC< / 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" > NC< / span > < span class = "plain-syntax" > > < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > Responses::enable_private_parking< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > R< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > marker< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < a href = "3-lp.html#SP5" class = "function-link" > < span class = "function-syntax" > LocalParking::array< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > NC< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "3-lp.html#SP2" class = "function-link" > < span class = "function-syntax" > LocalParking::park< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
< p class = "commentary firstcommentary" > < a id = "SP3" class = "paragraph-anchor" > < / a > < b > § 3. < / b > And this compiles the retrieval code just after B begins:
< / p >
< 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" > LocalParking::retrieve< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > stack_frame< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > inter_name< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > park< / span > < span class = "plain-syntax" > = < / span > < a href = "3-lp.html#SP5" class = "function-link" > < span class = "function-syntax" > LocalParking::array< / span > < / a > < span class = "plain-syntax" > (0, < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > inter_ti< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > j< / span > < span class = "plain-syntax" > =0;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > local_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > LOOP_OVER_LOCALS_IN_FRAME< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > frame< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::inv< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > STORE_BIP< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::down< / span > < span class = "plain-syntax" > ();< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::ref_symbol< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > K_value< / span > < span class = "plain-syntax" > , < / span > < a href = "3-lv.html#SP1" class = "function-link" > < span class = "function-syntax" > LocalVariables::declare< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lvar< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::inv< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > LOOKUP_BIP< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::down< / span > < span class = "plain-syntax" > ();< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::val_iname< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > K_value< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > park< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::val_number< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > j< / span > < span class = "plain-syntax" > ++);< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::up< / span > < span class = "plain-syntax" > ();< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitCode::up< / span > < span class = "plain-syntax" > ();< / span >
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< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP4" class = "paragraph-anchor" > < / a > < b > § 4. < / b > We support multiple different parking lots, though we almost always use a
single shared parking lot when we can prove that the values in it will not be
corrupted before use.
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< / p >
< pre class = "displayed-code all-displayed-code code-font" >
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< 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" > local_parking_lot< / 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" > capacity< / 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" > inter_name< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > storage_iname< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > CLASS_DEFINITION< / span >
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > shared_parking< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LocalParking::new_lot< / 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" > LocalParking::new_lot< / span > < / span > :< br / > < a href = "3-lp.html#SP5" > § 5< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > inter_name< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > iname< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > CREATE< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > capacity< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 2< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > storage_iname< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > iname< / 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" > lot< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
< ul class = "endnotetexts" > < li > The structure local_parking_lot is private to this section.< / li > < / ul >
< p class = "commentary firstcommentary" > < a id = "SP5" class = "paragraph-anchor" > < / a > < b > § 5. < / b > So, then, this returns the array to use for storage, ensuring that it has
a capacity of at least < span class = "extract" > < span class = "extract-syntax" > N< / span > < / span > , and therefore has entries in the range < span class = "extract" > < span class = "extract-syntax" > 0 < = x < N< / span > < / span > .
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "identifier-syntax" > inter_name< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LocalParking::array< / 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" > LocalParking::array< / span > < / span > :< br / > < a href = "3-lp.html#SP2" > § 2< / a > , < a href = "3-lp.html#SP3" > § 3< / a > , < a href = "3-lp.html#SP6" > § 6< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lot< / 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" > lot< / 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" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > shared_parking< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > shared_parking< / span > < span class = "plain-syntax" > = < / span > < a href = "3-lp.html#SP4" class = "function-link" > < span class = "function-syntax" > LocalParking::new_lot< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Hierarchy::find< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > LOCALPARKING_HL< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > shared_parking< / span > < span class = "plain-syntax" > ;< / 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" > N< / span > < span class = "plain-syntax" > > < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > capacity< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > capacity< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > N< / 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" > lot< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > storage_iname< / span > < span class = "plain-syntax" > ;< / span >
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< span class = "plain-syntax" > }< / span >
< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP6" class = "paragraph-anchor" > < / a > < b > § 6. < / b > We also sometimes use the shared parking lot to hold returned callings from
deferred propositions; and that needs to be large enough to hold values of
up to 26 variables, plus a single other value.
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< / p >
< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "identifier-syntax" > inter_name< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LocalParking::callings< / span > < button class = "popup" onclick = "togglePopup('usagePopup3')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup3" > Usage of < span class = "code-font" > < span class = "function-syntax" > LocalParking::callings< / span > < / span > :< br / > Deciding to Defer - < a href = "4-dtd.html#SP7" > § 7< / a > , < a href = "4-dtd.html#SP8" > § 8< / a > < br / > Compile Deferred Propositions - < a href = "4-cdp.html#SP3_6_1_4_5" > § 3.6.1.4.5< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "3-lp.html#SP5" class = "function-link" > < span class = "function-syntax" > LocalParking::array< / span > < / a > < span class = "plain-syntax" > (27, < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > }< / span >
< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP7" class = "paragraph-anchor" > < / a > < b > § 7. < / b > The parking lot(s) is/are initialised to arrays of zero values: their
contents are meaningless at the start of execution.
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< / p >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > LocalParking::compile_array< / span > < 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" > local_parking_lot< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > LOOP_OVER< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > local_parking_lot< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > packaging_state< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > save< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > EmitArrays::begin_word< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > lot< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > storage_iname< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > K_value< / span > < span class = "plain-syntax" > );< / span >
< 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" > < lot-> < / span > < span class = "element-syntax" > capacity< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > i< / span > < span class = "plain-syntax" > ++) < / span > < span class = "identifier-syntax" > EmitArrays::numeric_entry< / span > < span class = "plain-syntax" > (0);< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > EmitArrays::end< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > save< / span > < span class = "plain-syntax" > );< / span >
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< span class = "comment-syntax" > Hierarchy::make_available(lot-> storage_iname);< / span >
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< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
< nav role = "progress" > < div class = "progresscontainer" >
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< ul class = "progressbar" > < li class = "progressprev" > < a href = "3-tv.html" > ❮ < / a > < / li > < li class = "progresschapter" > < a href = "P-wtmd.html" > P< / a > < / li > < li class = "progresschapter" > < a href = "1-im.html" > 1< / a > < / li > < li class = "progresschapter" > < a href = "2-cv.html" > 2< / a > < / li > < li class = "progresscurrentchapter" > 3< / li > < li class = "progresssection" > < a href = "3-sf.html" > sf< / a > < / li > < li class = "progresssection" > < a href = "3-lvs.html" > lvs< / a > < / li > < li class = "progresssection" > < a href = "3-lv.html" > lv< / a > < / li > < li class = "progresssection" > < a href = "3-tv.html" > tv< / a > < / li > < li class = "progresscurrent" > lp< / li > < li class = "progresssection" > < a href = "3-cb.html" > cb< / a > < / li > < li class = "progresssection" > < a href = "3-fnc.html" > fnc< / a > < / li > < li class = "progresssection" > < a href = "3-jl.html" > jl< / a > < / li > < li class = "progresssection" > < a href = "3-pr.html" > pr< / a > < / li > < li class = "progresssection" > < a href = "3-cls.html" > cls< / a > < / li > < li class = "progresssection" > < a href = "3-cid.html" > cid< / a > < / li > < li class = "progresschapter" > < a href = "4-cs.html" > 4< / a > < / li > < li class = "progresschapter" > < a href = "5-cbal.html" > 5< / a > < / li > < li class = "progressnext" > < a href = "3-cb.html" > ❯ < / a > < / li > < / ul > < / div >
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< / nav > <!-- End of weave -->
< / main >
< / body >
< / html >