ref: 7c82ec25411d61a9cd70688f729c4b2f3e346e57
dir: /jsintern.c/
#include "jsi.h" /* Use an AA-tree to quickly look up interned strings. */ struct js_StringNode { js_StringNode *left, *right; int level; char string[1]; }; static js_StringNode sentinel = { &sentinel, &sentinel, 0, ""}; static js_StringNode *newstringnode(const char *string, const char **result) { int n = strlen(string); js_StringNode *node = malloc(offsetof(js_StringNode, string) + n + 1); node->left = node->right = &sentinel; node->level = 1; strcpy(node->string, string); return *result = node->string, node; } static js_StringNode *skew(js_StringNode *node) { if (node->level != 0) { if (node->left->level == node->level) { js_StringNode *save = node; node = node->left; save->left = node->right; node->right = save; } node->right = skew(node->right); } return node; } static js_StringNode *split(js_StringNode *node) { if (node->level != 0 && node->right->right->level == node->level) { js_StringNode *save = node; node = node->right; save->right = node->left; node->left = save; node->level++; node->right = split(node->right); } return node; } static js_StringNode *insert(js_StringNode *node, const char *string, const char **result) { if (node != &sentinel) { int c = strcmp(string, node->string); if (c < 0) node->left = insert(node->left, string, result); else if (c > 0) node->right = insert(node->right, string, result); else return *result = node->string, node; node = skew(node); node = split(node); return node; } return newstringnode(string, result); } static void dumpstringnode(js_StringNode *node, int level) { int i; if (node->left != &sentinel) dumpstringnode(node->left, level + 1); printf("%d: ", node->level); for (i = 0; i < level; ++i) putchar('\t'); printf("'%s'\n", node->string); if (node->right != &sentinel) dumpstringnode(node->right, level + 1); } void jsS_dumpstrings(js_State *J) { js_StringNode *root = J->strings; printf("interned strings {\n"); if (root && root != &sentinel) dumpstringnode(root, 1); printf("}\n"); } static void js_freestringnode(js_State *J, js_StringNode *node) { if (node->left != &sentinel) js_freestringnode(J, node->left); if (node->right != &sentinel) js_freestringnode(J, node->right); free(node); } void jsS_freestrings(js_State *J) { if (J->strings && J->strings != &sentinel) js_freestringnode(J, J->strings); } const char *js_intern(js_State *J, const char *s) { const char *result; if (!J->strings) J->strings = &sentinel; J->strings = insert(J->strings, s, &result); return result; }