100 lines
3.1 KiB
Plaintext
100 lines
3.1 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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/* $Id$ */
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/* EXPRESSION DESCRIPTOR */
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/* What we want to define is the struct expr, but since it contains
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a union of various goodies, we define them first; so be patient.
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*/
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/* classes of value */
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#define Const 1
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#define Name 2
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#define Label 3
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struct value {
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int vl_class; /* Const, Name or Label */
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arith vl_value; /* constant value or offset */
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union {
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struct idf *vl_idf; /* external name */
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label vl_lbl; /* compiler-generated label */
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} vl_data;
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};
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struct string {
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char *sg_value; /* row of bytes repr. the constant */
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int sg_len; /* length of the row */
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};
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struct oper {
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struct type *op_type; /* resulting type of the operation */
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struct expr *op_left;
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int op_oper; /* the symbol of the operator */
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struct expr *op_right;
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};
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/* The following constants indicate the class of the expression: */
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#define Value 0 /* it is a value known at load time */
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#define String 1 /* it is a string constant */
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#define Float 2 /* it is a floating point constant */
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#define Oper 3 /* it is a run-time expression */
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#define Type 4 /* only its type is relevant */
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struct expr {
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char *ex_file; /* the file it (probably) comes from */
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unsigned int ex_line; /* the line it (probably) comes from */
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struct type *ex_type;
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short ex_lvalue;
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short ex_flags;
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int ex_class;
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int ex_depth;
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union {
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struct value ex_value;
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struct string ex_string;
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flt_arith ex_fl_arith;
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struct oper ex_oper;
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} ex_object;
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};
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/* some abbreviated selections */
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#define EX_VALUE ex_object.ex_value
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#define VL_CLASS EX_VALUE.vl_class
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#define VL_VALUE EX_VALUE.vl_value
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#define VL_IDF EX_VALUE.vl_data.vl_idf
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#define VL_LBL EX_VALUE.vl_data.vl_lbl
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#define SG_VALUE ex_object.ex_string.sg_value
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#define SG_LEN ex_object.ex_string.sg_len
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#define FL_ARITH ex_object.ex_fl_arith
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#define OP_TYPE ex_object.ex_oper.op_type
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#define OP_LEFT ex_object.ex_oper.op_left
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#define OP_OPER ex_object.ex_oper.op_oper
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#define OP_RIGHT ex_object.ex_oper.op_right
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/* some bits for the ex_flag field, to keep track of various
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interesting properties of an expression.
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*/
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#define EX_SIZEOF 0x001 /* contains sizeof operator */
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#define EX_CAST 0x002 /* contains cast */
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#define EX_LOGICAL 0x004 /* contains logical operator */
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#define EX_COMMA 0x008 /* contains expression comma */
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#define EX_PARENS 0x010 /* the top level is parenthesized */
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#define EX_SIDEEFFECTS 0x020 /* expression has side effects */
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#define EX_READONLY 0x040 /* read only variabele */
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#define EX_VOLATILE 0x080 /* volatile variabele */
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#define EX_ILVALUE 0x100 /* an illegal lvalue e.g. f().x */
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#define EX_ERROR 0x200 /* the expression is wrong */
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#define EX_PTRDIFF 0x400 /* subtracting 2 pointers in expr. */
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#define NILEXPR ((struct expr *)0)
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/* some useful tests */
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#define ISNAME(e) ((e)->ex_class == Value && (e)->VL_CLASS == Name)
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#define ISCOMMA(e) ((e)->ex_class == Oper && (e)->OP_OPER == INITCOMMA)
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extern struct expr *intexpr(), *new_oper();
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/* ALLOCDEF "expr" 20 */
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