121 lines
2.4 KiB
C
121 lines
2.4 KiB
C
#include "mupdf/fitz.h"
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#include <string.h>
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/* AA-tree */
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struct fz_tree_s
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{
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char *key;
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void *value;
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fz_tree *left, *right;
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int level;
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};
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static fz_tree tree_sentinel = { "", NULL, &tree_sentinel, &tree_sentinel, 0 };
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static fz_tree *fz_tree_new_node(fz_context *ctx, const char *key, void *value)
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{
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fz_tree *node = fz_malloc_struct(ctx, fz_tree);
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fz_try(ctx)
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{
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node->key = fz_strdup(ctx, key);
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node->value = value;
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node->left = node->right = &tree_sentinel;
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node->level = 1;
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}
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fz_catch(ctx)
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{
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fz_free(ctx, node);
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fz_rethrow(ctx);
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}
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return node;
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}
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void *fz_tree_lookup(fz_context *ctx, fz_tree *node, const char *key)
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{
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if (node)
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{
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while (node != &tree_sentinel)
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{
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int c = strcmp(key, node->key);
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if (c == 0)
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return node->value;
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else if (c < 0)
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node = node->left;
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else
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node = node->right;
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}
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}
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return NULL;
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}
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static fz_tree *fz_tree_skew(fz_tree *node)
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{
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if (node->level != 0)
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{
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if (node->left->level == node->level)
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{
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fz_tree *save = node;
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node = node->left;
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save->left = node->right;
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node->right = save;
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}
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node->right = fz_tree_skew(node->right);
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}
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return node;
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}
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static fz_tree *fz_tree_split(fz_tree *node)
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{
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if (node->level != 0 && node->right->right->level == node->level)
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{
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fz_tree *save = node;
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node = node->right;
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save->right = node->left;
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node->left = save;
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node->level++;
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node->right = fz_tree_split(node->right);
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}
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return node;
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}
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/*
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Insert a new key/value pair and rebalance the tree.
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Return the new root of the tree after inserting and rebalancing.
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May be called with a NULL root to create a new tree.
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*/
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fz_tree *fz_tree_insert(fz_context *ctx, fz_tree *node, const char *key, void *value)
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{
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if (node && node != &tree_sentinel)
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{
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int c = strcmp(key, node->key);
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if (c < 0)
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node->left = fz_tree_insert(ctx, node->left, key, value);
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else
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node->right = fz_tree_insert(ctx, node->right, key, value);
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node = fz_tree_skew(node);
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node = fz_tree_split(node);
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return node;
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}
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else
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{
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return fz_tree_new_node(ctx, key, value);
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}
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}
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void fz_drop_tree(fz_context *ctx, fz_tree *node, void (*dropfunc)(fz_context *ctx, void *value))
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{
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if (node)
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{
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if (node->left != &tree_sentinel)
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fz_drop_tree(ctx, node->left, dropfunc);
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if (node->right != &tree_sentinel)
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fz_drop_tree(ctx, node->right, dropfunc);
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fz_free(ctx, node->key);
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if (dropfunc)
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dropfunc(ctx, node->value);
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fz_free(ctx, node);
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}
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}
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