mirror of https://github.com/lua/lua
140 lines
2.7 KiB
C
140 lines
2.7 KiB
C
/*
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** tree.c
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** TecCGraf - PUC-Rio
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*/
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char *rcs_tree="$Id: tree.c,v 1.7 1994/11/16 18:09:11 roberto Exp roberto $";
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#include <string.h>
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#include "mem.h"
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#include "lua.h"
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#include "tree.h"
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#include "table.h"
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#define lua_strcmp(a,b) (a[0]<b[0]?(-1):(a[0]>b[0]?(1):strcmp(a,b)))
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typedef struct StringNode {
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struct StringNode *next;
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Word mark;
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char str[1];
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} StringNode;
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static StringNode *string_root = NULL;
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static TreeNode *constant_root = NULL;
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/*
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** Insert a new constant/variable at the tree.
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*/
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static TreeNode *tree_create (TreeNode **node, char *str)
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{
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if (*node == NULL)
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{
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*node = (TreeNode *) luaI_malloc(sizeof(TreeNode)+strlen(str));
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(*node)->left = (*node)->right = NULL;
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strcpy((*node)->str, str);
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(*node)->varindex = (*node)->constindex = UNMARKED_STRING;
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return *node;
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}
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else
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{
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int c = lua_strcmp(str, (*node)->str);
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if (c < 0)
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return tree_create(&(*node)->left, str);
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else if (c > 0)
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return tree_create(&(*node)->right, str);
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else
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return *node;
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}
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}
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char *lua_strcreate (char *str)
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{
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StringNode *newString;
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lua_pack();
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newString = (StringNode *)luaI_malloc(sizeof(StringNode)+strlen(str));
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newString->mark = UNMARKED_STRING;
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strcpy(newString->str, str);
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newString->next = string_root;
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string_root = newString;
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return newString->str;
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}
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TreeNode *lua_constcreate (char *str)
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{
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return tree_create(&constant_root, str);
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}
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/*
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** Garbage collection function.
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** This function traverse the string list freeing unindexed strings
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*/
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int lua_strcollector (void)
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{
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StringNode *curr = string_root, *prev = NULL;
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int counter = 0;
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while (curr)
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{
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StringNode *next = curr->next;
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if (curr->mark == UNMARKED_STRING)
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{
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if (prev == NULL) string_root = next;
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else prev->next = next;
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luaI_free(curr);
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++counter;
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}
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else
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{
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curr->mark = UNMARKED_STRING;
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prev = curr;
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}
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curr = next;
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}
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return counter;
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}
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/*
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** Return next variable.
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*/
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static TreeNode *tree_next (TreeNode *node, char *str)
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{
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if (node == NULL) return NULL;
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else if (str == NULL) return node;
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else
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{
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int c = lua_strcmp(str, node->str);
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if (c == 0)
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return node->left != NULL ? node->left : node->right;
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else if (c < 0)
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{
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TreeNode *result = tree_next(node->left, str);
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return result != NULL ? result : node->right;
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}
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else
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return tree_next(node->right, str);
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}
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}
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TreeNode *lua_varnext (char *n)
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{
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TreeNode *result;
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char *name = n;
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while (1)
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{ /* repeat until a valid (non nil) variable */
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result = tree_next(constant_root, name);
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if (result == NULL) return NULL;
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if (result->varindex != UNMARKED_STRING &&
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s_tag(result->varindex) != LUA_T_NIL)
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return result;
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name = result->str;
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}
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}
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