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ast.c
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1992-12-08
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/* Abstract syntax tree manipulation functions
*
* SOFTWARE RIGHTS
*
* We reserve no LEGAL rights to the Purdue Compiler Construction Tool
* Set (PCCTS) -- PCCTS is in the public domain. An individual or
* company may do whatever they wish with source code distributed with
* PCCTS or the code generated by PCCTS, including the incorporation of
* PCCTS, or its output, into commerical software.
*
* We encourage users to develop software with PCCTS. However, we do ask
* that credit is given to us for developing PCCTS. By "credit",
* we mean that if you incorporate our source code into one of your
* programs (commercial product, research project, or otherwise) that you
* acknowledge this fact somewhere in the documentation, research report,
* etc... If you like PCCTS and have developed a nice tool with the
* output, please mention that you developed it using PCCTS. In
* addition, we ask that this header remain intact in our source code.
* As long as these guidelines are kept, we expect to continue enhancing
* this system and expect to make other tools available as they are
* completed.
*
* ANTLR 1.06
* Terence Parr
* Purdue University
* 1989-1992
*/
#ifdef __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
/* ensure that tree manipulation variables are current after a rule
* reference
*/
void
zzlink(_root, _sibling, _tail)
AST **_root, **_sibling, **_tail;
{
if ( *_sibling == NULL ) return;
if ( *_root == NULL ) *_root = *_sibling;
else if ( *_root != *_sibling ) (*_root)->down = *_sibling;
if ( *_tail==NULL ) *_tail = *_sibling;
while ( (*_tail)->right != NULL ) *_tail = (*_tail)->right;
}
AST *
zzastnew()
{
#ifdef __STDC__
extern char *calloc(unsigned, unsigned);
#else
extern char *calloc();
#endif
AST *p = (AST *) calloc(1, sizeof(AST));
if ( p == NULL ) fprintf(stderr,"%s(%d): cannot allocate AST node\n",__FILE__,__LINE__);
return p;
}
/* add a child node to the current sibling list */
void
zzsubchild(_root, _sibling, _tail)
AST **_root, **_sibling, **_tail;
{
AST *n = zzastnew();
#ifdef DEMAND_LOOK
zzcr_ast(n, &(zzaCur), LA(0), LATEXT(0));
#else
zzcr_ast(n, &(zzaCur), LA(1), LATEXT(1));
#endif
zzastPush( n );
if ( *_tail != NULL ) (*_tail)->right = n;
else {
*_sibling = n;
if ( *_root != NULL ) (*_root)->down = *_sibling;
}
*_tail = n;
if ( *_root == NULL ) *_root = *_sibling;
}
/* make a new AST node. Make the newly-created
* node the root for the current sibling list. If a root node already
* exists, make the newly-created node the root of the current root.
*/
void
zzsubroot(_root, _sibling, _tail)
AST **_root, **_sibling, **_tail;
{
AST *n = zzastnew();
#ifdef DEMAND_LOOK
zzcr_ast(n, &(zzaCur), LA(0), LATEXT(0));
#else
zzcr_ast(n, &(zzaCur), LA(1), LATEXT(1));
#endif
zzastPush( n );
if ( *_root != NULL )
if ( (*_root)->down == *_sibling ) *_sibling = *_tail = *_root;
*_root = n;
(*_root)->down = *_sibling;
}
/* Apply function to root then each sibling
* example: print tree in child-sibling LISP-format (AST has token field)
*
* void show(tree)
* AST *tree;
* {
* if ( tree == NULL ) return;
* printf(" %s", zztokens[tree->token]);
* }
*
* void before() { printf(" ("); }
* void after() { printf(" )"); }
*
* LISPdump() { zzpre_ast(tree, show, before, after); }
*
*/
void
zzpre_ast(tree, func, before, after)
AST *tree;
void (*func)(), /* apply this to each tree node */
(*before)(), /* apply this to root of subtree before preordering it */
(*after)(); /* apply this to root of subtree after preordering it */
{
while ( tree!= NULL )
{
if ( tree->down != NULL ) (*before)(tree);
(*func)(tree);
zzpre_ast(tree->down, func, before, after);
if ( tree->down != NULL ) (*after)(tree);
tree = tree->right;
}
}
/* free all AST nodes in tree; apply func to each before freeing */
void
zzfree_ast(tree)
AST *tree;
{
if ( tree == NULL ) return;
zzfree_ast( tree->down );
zzfree_ast( tree->right );
zztfree( tree );
}
/* build a tree (root child1 child2 ... NULL)
* If root is NULL, simply make the children siblings and return ptr
* to 1st sibling (child1). If root is not single node, return NULL.
*
* Siblings that are actually siblins lists themselves are handled
* correctly. For example #( NULL, #( NULL, A, B, C), D) results
* in the tree ( NULL A B C D ).
*
* Requires at least two parameters with the last one being NULL. If
* both are NULL, return NULL.
*/
#ifdef __STDC__
AST *zztmake(AST *rt, ...)
#else
AST *zztmake(va_alist)
va_dcl
#endif
{
va_list ap;
register AST *child, *sibling=NULL, *tail, *w;
AST *root;
#ifdef __STDC__
va_start(ap, rt);
root = rt;
#else
va_start(ap);
root = va_arg(ap, AST *);
#endif
if ( root != NULL )
if ( root->down != NULL ) return NULL;
child = va_arg(ap, AST *);
while ( child != NULL )
{
for (w=child; w->right!=NULL; w=w->right) {;} /* find end of child */
if ( sibling == NULL ) {sibling = child; tail = w;}
else {tail->right = child; tail = w;}
child = va_arg(ap, AST *);
}
if ( root==NULL ) root = sibling;
else root->down = sibling;
va_end(ap);
return root;
}
/* tree duplicate */
AST *
zzdup_ast(t)
AST *t;
{
AST *u;
if ( t == NULL ) return NULL;
u = zzastnew();
*u = *t;
u->right = zzdup_ast(t->right);
u->down = zzdup_ast(t->down);
return u;
}
void
zztfree(t)
AST *t;
{
#ifdef zzd_ast
zzd_ast( t );
#endif
free( t );
}
#ifdef zzAST_DOUBLE
/*
* Set the 'up', and 'left' pointers of all nodes in 't'.
* USER MUST CREATE up, left FIELDS using AST_FIELDS macro.
* Initial call is double_link(your_tree, NULL, NULL).
*/
void
zzdouble_link(t, left, up)
AST *t, *left, *up;
{
if ( t==NULL ) return;
t->left = left;
t->up = up;
zzdouble_link(t->down, NULL, t);
zzdouble_link(t->right, t, up);
}
#endif