ack/lang/pc/comp/lookup.c
1988-10-26 15:21:11 +00:00

66 lines
1.4 KiB
C

/* L O O K U P R O U T I N E S */
#include <em_arith.h>
#include <em_label.h>
#include "LLlex.h"
#include "def.h"
#include "idf.h"
#include "misc.h"
#include "node.h"
#include "scope.h"
#include "type.h"
struct def *
lookup(id, scope)
register struct idf *id;
struct scope *scope;
{
/* Look up a definition of an identifier in scope "scope".
Make the "def" list self-organizing.
Return a pointer to its "def" structure if it exists,
otherwise return 0.
*/
register struct def *df, *df1;
/* Look in the chain of definitions of this "id" for one with scope
"scope".
*/
for( df = id->id_def, df1 = 0;
df && df->df_scope != scope;
df1 = df, df = df->df_next ) { /* nothing */ }
if( df && df1 ) {
/* Put the definition in front
*/
df1->df_next = df->df_next;
df->df_next = id->id_def;
id->id_def = df;
}
return df;
}
struct def *
lookfor(id, vis, give_error)
register struct node *id;
struct scopelist *vis;
{
/* Look for an identifier in the visibility range started by "vis".
If it is not defined create a dummy definition and
if give_error is set, give an error message.
*/
register struct def *df;
register struct scopelist *sc = vis;
while( sc ) {
df = lookup(id->nd_IDF, sc->sc_scope);
if( df ) return df;
sc = nextvisible(sc);
}
if( give_error ) id_not_declared(id);
df = MkDef(id->nd_IDF, vis->sc_scope, D_ERROR);
return df;
}