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- /* $Header$ */
- /* EXPRESSION DESCRIPTOR */
- /* What we want to define is the struct expr, but since it contains
- a union of various goodies, we define them first; so be patient.
- */
- struct value {
- struct idf *vl_idf; /* idf of an external name or 0 */
- arith vl_value; /* constant, or offset if idf != 0 */
- };
- struct string {
- char *sg_value; /* string of characters repr. the constant */
- label sg_datlab; /* global data-label */
- };
- struct floating {
- char *fl_value; /* pointer to string repr. the fp const. */
- label fl_datlab; /* global data_label */
- };
- struct oper {
- struct type *op_type; /* resulting type of the operation */
- struct expr *op_left;
- int op_oper; /* the symbol of the operator */
- struct expr *op_right;
- };
- /* The following constants indicate the class of the expression: */
- #define Value 0 /* it is a value known at load time */
- #define String 1 /* it is a string constant */
- #define Float 2 /* it is a floating point constant */
- #define Oper 3 /* it is a run-time expression */
- #define Type 4 /* only its type is relevant */
- struct expr {
- struct expr *next;
- char *ex_file; /* the file it (probably) comes from */
- unsigned int ex_line; /* the line it (probably) comes from */
- struct type *ex_type;
- char ex_lvalue;
- char ex_flags;
- int ex_class;
- int ex_depth;
- union {
- struct value ex_value;
- struct string ex_string;
- struct floating ex_float;
- struct oper ex_oper;
- } ex_object;
- };
- /* some abbreviated selections */
- #define VL_VALUE ex_object.ex_value.vl_value
- #define VL_IDF ex_object.ex_value.vl_idf
- #define SG_VALUE ex_object.ex_string.sg_value
- #define SG_DATLAB ex_object.ex_string.sg_datlab
- #define FL_VALUE ex_object.ex_float.fl_value
- #define FL_DATLAB ex_object.ex_float.fl_datlab
- #define OP_TYPE ex_object.ex_oper.op_type
- #define OP_LEFT ex_object.ex_oper.op_left
- #define OP_OPER ex_object.ex_oper.op_oper
- #define OP_RIGHT ex_object.ex_oper.op_right
- #define EXPRTYPE(e) ((e)->ex_type->tp_fund)
- /* An expression is a `load-time constant' if it is of the form
- <idf> +/- <integral> or <integral>;
- it is a `compile-time constant' if it is an <integral>.
- */
- #define is_ld_cst(e) ((e)->ex_lvalue == 0 && (e)->ex_class == Value)
- #define is_cp_cst(e) (is_ld_cst(e) && (e)->VL_IDF == 0)
- /* a floating constant expression ?
- */
- #define is_fp_cst(e) ((e)->ex_class == Float)
- /* some bits for the ex_flag field, to keep track of various
- interesting properties of an expression.
- */
- #define EX_SIZEOF 001 /* contains sizeof operator */
- #define EX_CAST 002 /* contains cast */
- #define EX_LOGICAL 004 /* contains logical operator */
- #define EX_COMMA 010 /* contains expression comma */
- #define EX_PARENS 020 /* the top level is parenthesized */
- #define NILEXPR ((struct expr *)0)
- extern struct expr *intexpr(), *new_oper();
- /* allocation definitions of struct expr */
- /* ALLOCDEF "expr" */
- extern char *st_alloc();
- extern struct expr *h_expr;
- #define new_expr() ((struct expr *) \
- st_alloc((char **)&h_expr, sizeof(struct expr)))
- #define free_expr(p) st_free(p, h_expr, sizeof(struct expr))
- #define ISCOMMA(e) ((e)->ex_class == Oper && (e)->OP_OPER == INITCOMMA)
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