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133 lines
1.9 KiB
133 lines
1.9 KiB
grammar t022scopes;
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options {
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language=JavaScript;
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}
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/* global scopes */
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scope aScope {
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names
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}
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a
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scope aScope;
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: {$aScope::names = [];} ID*
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;
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/* rule scopes, from the book, final beta, p.147 */
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b[v]
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scope {x}
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: {$b::x = v;} b2
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;
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b2
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: b3
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;
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b3
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: {$b::x}?=> ID // only visible, if b was called with True
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| NUM
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;
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/* rule scopes, from the book, final beta, p.148 */
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c returns [res]
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scope {
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symbols
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}
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@init {
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$c::symbols = {};
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}
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: '{' c1* c2+ '}'
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{ $res = $c::symbols; }
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;
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c1
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: 'int' ID {$c::symbols[$ID.text] = true;} ';'
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;
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c2
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: ID '=' NUM ';'
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{
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if (! $c::symbols[$ID.text]) {
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throw new Error($ID.text);
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}
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}
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;
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/* recursive rule scopes, from the book, final beta, p.150 */
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d returns [res]
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scope {
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symbols
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}
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@init {
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$d::symbols = {};
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}
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: '{' d1* d2* '}'
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{ $res = $d::symbols; }
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;
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d1
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: 'int' ID {$d::symbols[$ID.text] = true;} ';'
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;
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d2
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: ID '=' NUM ';'
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{
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var i, isDefined;
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for (i=$d.length-1, isDefined=false; i>=0; i--) {
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if ($d[i]::symbols[$ID.text]) {
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isDefined = true;
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break;
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}
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}
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if (!isDefined) {
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throw new Error("undefined variable "+$ID.text);
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}
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}
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| d
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;
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/* recursive rule scopes, access bottom-most scope */
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e returns [res]
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scope {
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a
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}
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@after {
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$res = $e::a;
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}
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: NUM { $e[0]::a = parseInt($NUM.text, 10); }
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| '{' e '}'
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;
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/* recursive rule scopes, access with negative index */
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f returns [res]
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scope {
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a
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}
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@after {
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$res = $f::a;
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}
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: NUM { var len = $f.length-2; $f[len>=0 ? len : 0]::a = parseInt($NUM.text, 10); }
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| '{' f '}'
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;
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/* tokens */
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ID : ('a'..'z')+
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;
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NUM : ('0'..'9')+
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;
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WS : (' '|'\n'|'\r')+ {$channel=HIDDEN;}
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;
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