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erikb
371
lang/cem/cemcom/expression.g
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371
lang/cem/cemcom/expression.g
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/* $Header$ */
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/* EXPRESSION SYNTAX PARSER */
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{
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#include "arith.h"
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#include "LLlex.h"
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#include "type.h"
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#include "idf.h"
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#include "label.h"
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#include "expr.h"
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extern char options[];
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extern struct expr *intexpr();
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}
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/* 7 */
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initial_value(struct expr **expp;) :
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[
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assignment_expression(expp)
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{
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if ((*expp)->ex_type->tp_fund == ARRAY)
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array2pointer(expp);
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}
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initial_value_pack(expp)
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]
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;
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initial_value_pack(struct expr **expp;) :
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'{'
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initial_value_list(expp)
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'}'
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;
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initial_value_list(struct expr **expp;)
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{struct expr *e1;}
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:
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{*expp = NILEXPR;}
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initial_value(&e1)
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{init_expression(&expp, e1);}
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[%while (AHEAD != '}') /* >>> conflict on ',' */
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','
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initial_value(&e1)
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{init_expression(&expp, e1);}
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]*
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','? /* optional trailing comma */
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;
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/* 7.1 */
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primary(struct expr **expp;) :
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[
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IDENTIFIER
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{dot2expr(expp);}
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constant(expp)
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STRING
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{dot2expr(expp);}
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'(' expression(expp) ')'
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{(*expp)->ex_flags |= EX_PARENS;}
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]
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;
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secundary(struct expr **expp;) :
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primary(expp)
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[
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index_pack(expp)
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parameter_pack(expp)
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selection(expp)
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]*
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;
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index_pack(struct expr **expp;)
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{struct expr *e1;}
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:
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'[' expression(&e1) ']'
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{ch7bin(expp, '[', e1);}
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;
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parameter_pack(struct expr **expp;)
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{struct expr *e1 = 0;}
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:
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'(' parameter_list(&e1)? ')'
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{ch7bin(expp, '(', e1);}
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;
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selection(struct expr **expp;)
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{int oper; struct idf *idf;}
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:
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[ '.' | ARROW ]
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{oper = DOT;}
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identifier(&idf)
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{ch7sel(expp, oper, idf);}
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;
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parameter_list(struct expr **expp;)
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{struct expr *e1 = 0;}
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:
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assignment_expression(expp)
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{any2opnd(expp, PARCOMMA);}
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[ ','
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assignment_expression(&e1)
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{any2opnd(&e1, PARCOMMA);}
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{ch7bin(expp, PARCOMMA, e1);}
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]*
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;
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/* 7.2 */
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postfixed(struct expr **expp;)
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{int oper;}
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:
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secundary(expp)
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[
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postop(&oper)
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{ch7incr(expp, oper);}
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empty
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]
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;
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%first first_of_type_specifier, type_specifier;
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unary(struct expr **expp;)
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{struct type *tp; int oper;}
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:
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[%if (first_of_type_specifier(AHEAD))
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cast(&tp) unary(expp)
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{ ch7cast(expp, CAST, tp);
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(*expp)->ex_flags |= EX_CAST;
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}
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postfixed(expp)
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unop(&oper) unary(expp)
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{ch7mon(oper, expp);}
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size_of(expp)
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]
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;
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size_of(struct expr **expp;)
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{struct type *tp;}
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:
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SIZEOF
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[%if (first_of_type_specifier(AHEAD))
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cast(&tp)
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{
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*expp = intexpr(size_of_type(tp, "type"), INT);
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(*expp)->ex_flags |= EX_SIZEOF;
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}
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unary(expp)
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{ch7mon(SIZEOF, expp);}
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]
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;
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/* 7.3-7.12 */
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/* The set of operators in C is stratified in 15 levels, with level
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N being treated in RM 7.N. In principle each operator is
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assigned a rank, ranging from 1 to 15. Such an expression can
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be parsed by a construct like:
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binary_expression(int maxrank;)
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{int oper;}
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:
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binary_expression(maxrank - 1)
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[%if (rank_of(DOT) <= maxrank)
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binop(&oper)
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binary_expression(rank_of(oper)-1)
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]?
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;
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except that some call of 'unary' is necessary, depending on the
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grammar.
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This simple view is marred by three complications:
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1. Level 15 (comma operator) is not allowed in many
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contexts and is different.
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2. Level 13 (conditional operator) is a ternary operator,
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which does not fit this scheme at all.
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3. Level 14 (assignment operators) group right-to-left, as
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opposed to 2-12, which group left-to-right (or are
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immaterial).
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4. The operators in level 14 start with operators in levels
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2-13 (RM 7.14: The two parts of a compound assignment
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operator are separate tokens.) This causes LL1 problems.
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This forces us to have four rules:
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binary_expression for level 2-12
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conditional_expression for level 13
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assignment_expression for level 14 and
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expression for the most general expression
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*/
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binary_expression(int maxrank; struct expr **expp;)
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{int oper; struct expr *e1;}
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:
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unary(expp)
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[%while (rank_of(DOT) <= maxrank && AHEAD != '=')
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/* '?', '=', and ',' are no binops, and the test
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for AHEAD != '=' keeps the other assignment
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operators out
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*/
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binop(&oper)
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binary_expression(rank_of(oper)-1, &e1)
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{
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ch7bin(expp, oper, e1);
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}
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]*
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;
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/* 7.13 */
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conditional_expression(struct expr **expp;)
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/* There is some unfortunate disagreement about what is allowed
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between the '?' and the ':' of a conditional_expression.
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Although the Ritchie compiler does not even allow
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conditional_expressions there, some other compilers (e.g., VAX)
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accept a full assignment_expression there, and programs
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(like, e.g., emacs) rely on it. So we have little choice.
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*/
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{struct expr *e1 = 0, *e2 = 0;}
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:
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/* allow all binary operators */
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binary_expression(rank_of('?') - 1, expp)
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[ '?'
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expression(&e1)
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{check_conditional(e1, '?', "between ? and :");}
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':'
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assignment_expression(&e2)
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{check_conditional(e2, '=', "after :");}
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{
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ch7bin(&e1, ':', e2);
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opnd2test(expp, NOTEQUAL);
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ch7bin(expp, '?', e1);
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}
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]?
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;
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/* 7.14 */
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assignment_expression(struct expr **expp;)
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{
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int oper;
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struct expr *e1 = 0;
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}
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:
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conditional_expression(expp)
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[%prefer /* (rank_of(DOT) <= maxrank) for any asgnop */
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asgnop(&oper)
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assignment_expression(&e1)
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{ch7asgn(expp, oper, e1);}
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empty /* LLgen artefact ??? */
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]
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;
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/* 7.15 */
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expression(struct expr **expp;)
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{struct expr *e1;}
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:
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assignment_expression(expp)
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[ ','
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assignment_expression(&e1)
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{
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ch7bin(expp, ',', e1);
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}
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]*
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;
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unop(int *oper;) :
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['*' | '&' | '-' | '!' | '~' | PLUSPLUS | MINMIN]
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{*oper = DOT;}
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;
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postop(int *oper;):
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[
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PLUSPLUS {*oper = POSTINCR;}
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MINMIN {*oper = POSTDECR;}
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]
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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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asgnop(int *oper;):
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[
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'=' {*oper = DOT;}
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'+' '=' {*oper = PLUSAB;}
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'-' '=' {*oper = MINAB;}
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'*' '=' {*oper = TIMESAB;}
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'/' '=' {*oper = DIVAB;}
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'%' '=' {*oper = MODAB;}
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LEFT '=' {*oper = LEFTAB;}
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RIGHT '=' {*oper = RIGHTAB;}
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'&' '=' {*oper = ANDAB;}
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'^' '=' {*oper = XORAB;}
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'|' '=' {*oper = ORAB;}
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[ PLUSAB | MINAB | TIMESAB | DIVAB | MODAB |
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LEFTAB | RIGHTAB | ANDAB | XORAB | ORAB ]
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{
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char *symbol2str();
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warning("old-fashioned assignment operator, use %s",
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symbol2str(DOT));
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*oper = DOT;
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}
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]
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;
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constant(struct expr **expp;) :
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[
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INTEGER
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FLOATING
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] {dot2expr(expp);}
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;
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/* 15 */
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constant_expression (struct expr **expp;) :
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assignment_expression(expp)
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{chk_cst_expr(expp);}
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;
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identifier(struct idf **idfp;) :
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[
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IDENTIFIER
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TYPE_IDENTIFIER
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]
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{*idfp = dot.tk_idf;}
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;
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