/* 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 commercial 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 1.33
 * Terence Parr
 * Parr Research Corporation
 * with Purdue University and AHPCRC, University of Minnesota
 * 1989-1995
 */
#include <stdarg.h>
#include <stdio.h>

#include "ast.h"
#include "attrib.h"
#include "antlr.h"

/* ensure that tree manipulation variables are current after a rule
 * reference
 */
void
zzlink(AST **_root, AST **_sibling, AST **_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(void)
{
	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(AST **_root, AST **_sibling, AST **_tail)
{
	AST *n;
	zzNON_GUESS_MODE {
	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(AST **_root, AST **_sibling, AST **_tail)
{
	AST *n;
	zzNON_GUESS_MODE {
	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(
	  AST *tree,
	  void (*func)(AST *),   /* apply this to each tree node */
	  void (*before)(AST *), /* apply this to root of subtree before preordering it */
	  void (*after)(AST *))  /* 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(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.
 */
AST *zztmake(AST *rt, ...)
{
	va_list ap;
	register AST *child, *sibling=NULL, *tail, *w;
	AST *root;

	va_start(ap, rt);
	root = rt;

	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(AST *t)
{
	AST *u;
	
	if ( t == NULL ) return NULL;
	u = zzastnew();
	*u = *t;
#ifdef zzAST_DOUBLE
	u->up = NULL;		/* set by calling invocation */
	u->left = NULL;
#endif
	u->right = zzdup_ast(t->right);
	u->down = zzdup_ast(t->down);
#ifdef zzAST_DOUBLE
	if ( u->right!=NULL ) u->right->left = u;
	if ( u->down!=NULL ) u->down->up = u;
#endif
	return u;
}

void
zztfree(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'.
 * Initial call is double_link(your_tree, NULL, NULL).
 */
void
zzdouble_link(AST *t, AST *left, AST *up)
{
	if ( t==NULL ) return;
	t->left = left;
	t->up = up;
	zzdouble_link(t->down, NULL, t);
	zzdouble_link(t->right, t, up);
}
#endif
