87 lines
1.7 KiB
C
87 lines
1.7 KiB
C
/* D E F I N I T I O N M E C H A N I S M */
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static char *RcsId = "$Header$";
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#include <alloc.h>
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#include <em_arith.h>
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#include <em_label.h>
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#include "Lpars.h"
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#include "def.h"
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#include "idf.h"
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#include "main.h"
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#include "scope.h"
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struct def *h_def; /* Pointer to free list of def structures */
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struct def *
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define(id, scope, kind)
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register struct idf *id;
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register struct scope *scope;
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{
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/* Declare an identifier in a scope, but first check if it
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already has been defined. If so, error message.
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*/
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register struct def *df = lookup(id, scope->sc_scope);
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if ( /* Already in this scope */
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df
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|| /* A closed scope, and id defined in the pervasive scope */
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(scopeclosed(scope) && (df = lookup(id, 0)))
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) {
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switch(df->df_kind) {
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case D_PROCHEAD:
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if (kind == D_PROCEDURE) {
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df->df_kind = D_PROCEDURE;
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return df;
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}
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break;
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case D_HIDDEN:
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if (kind == D_TYPE && state == IMPLEMENTATION) {
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df->df_kind = D_HTYPE;
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return df;
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}
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break;
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case D_ISEXPORTED:
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df->df_kind = kind;
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return df;
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break;
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}
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error("Identifier %s already declared", id->id_text);
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return df;
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}
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df = new_def();
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df->df_idf = id;
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df->df_scope = scope->sc_scope;
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df->df_kind = kind;
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df->next = id->id_def;
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id->id_def = df;
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return df;
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}
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struct def *
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lookup(id, scope)
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register struct idf *id;
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{
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/* Look up a definition of an identifier in scope "scope".
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Make the "def" list self-organizing.
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Return a pointer to its "def" structure if it exists,
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otherwise return 0.
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*/
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register struct def *df, *df1;
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df1 = 0;
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df = id->id_def;
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while (df) {
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if (df->df_scope == scope) {
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if (df1) {
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df1->next = df->next;
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df->next = id->id_def;
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id->id_def = df;
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}
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return df;
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}
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df = df->next;
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}
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return 0;
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}
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