mirror of https://github.com/lua/lua
124 lines
2.4 KiB
C
124 lines
2.4 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 1.13 1995/01/12 14:19:04 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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TaggedString ts;
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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)->ts.str, str);
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(*node)->ts.marked = 0;
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(*node)->ts.hash = 0;
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(*node)->varindex = (*node)->constindex = NOT_USED;
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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)->ts.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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TaggedString *lua_createstring (char *str)
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{
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StringNode *newString;
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if (str == NULL) return NULL;
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lua_pack();
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newString = (StringNode *)luaI_malloc(sizeof(StringNode)+strlen(str));
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newString->ts.marked = 0;
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newString->ts.hash = 0;
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strcpy(newString->ts.str, str);
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newString->next = string_root;
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string_root = newString;
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return &(newString->ts);
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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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Long lua_strcollector (void)
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{
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StringNode *curr = string_root, *prev = NULL;
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Long 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->ts.marked)
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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->ts.marked = 0;
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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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** Traverse the constant tree looking for a specific symbol number
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*/
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static TreeNode *nodebysymbol (TreeNode *root, Word symbol)
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{
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TreeNode *t;
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if (root == NULL) return NULL;
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if (root->varindex == symbol) return root;
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t = nodebysymbol(root->left, symbol);
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if (t) return t;
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return nodebysymbol(root->right, symbol);
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}
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TreeNode *luaI_nodebysymbol (Word symbol)
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{
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return nodebysymbol(constant_root, symbol);
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}
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