130 lines
1.7 KiB
Plaintext
130 lines
1.7 KiB
Plaintext
/*
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* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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/* EXPRESSION SYNTAX PARSER */
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%lexical LLlex;
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%start If_expr, if_expression;
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{
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#include "arith.h"
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#include "LLlex.h"
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extern arith ifval;
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}
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if_expression
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:
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constant_expression(&ifval)
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;
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/* 7.1 */
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primary(arith *pval;)
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:
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constant(pval)
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'(' expression(pval) ')'
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;
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unary(arith *pval;)
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{int oper;}
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:
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unop(&oper)
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unary(pval)
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{ ch3mon(oper, pval); }
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primary(pval)
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;
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binary_expression(int maxrank; arith *pval;)
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{int oper; arith val1;}
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:
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unary(pval)
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[%while (rank_of(DOT) <= maxrank)
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binop(&oper)
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binary_expression(rank_of(oper)-1, &val1)
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{
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ch3bin(pval, oper, val1);
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}
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]*
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;
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/* 7.13 */
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conditional_expression(arith *pval;)
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{arith val1 = 0, val2 = 0;}
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:
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/* allow all binary operators */
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binary_expression(rank_of('?') - 1, pval)
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[ '?'
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expression(&val1)
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':'
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assignment_expression(&val2)
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{ *pval = (*pval ? val1 : val2); }
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]?
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;
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/* 7.14 */
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assignment_expression(arith *pval;)
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:
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conditional_expression(pval)
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;
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/* 7.15 */
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expression(arith *pval;)
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{arith val1;}
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:
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assignment_expression(pval)
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[ ','
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assignment_expression(&val1)
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{
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ch3bin(pval, ',', val1);
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}
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]*
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;
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unop(int *oper;) :
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[ '-' | '!' | '~' ]
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{*oper = DOT;}
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;
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multop:
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'*' | '/' | '%'
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;
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addop:
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'+' | '-'
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;
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shiftop:
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LEFT | RIGHT
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;
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relop:
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'<' | '>' | LESSEQ | GREATEREQ
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;
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eqop:
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EQUAL | NOTEQUAL
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;
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arithop:
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multop | addop | shiftop
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'&' | '^' | '|'
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;
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binop(int *oper;) :
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[ arithop | relop | eqop | AND | OR ]
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{*oper = DOT;}
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;
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constant(arith *pval;) :
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INTEGER
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{*pval = dot.tk_val;}
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;
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constant_expression (arith *pval;) :
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assignment_expression(pval)
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;
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