Initial Commit

lenv.c

@@ -0,0 +1,92 @@
+#include <stdlib.h>
+#include <bits/stdlib-bsearch.h>
+
+#include "lang.h"
+#include "util.h"
+
+lenv* lenv_new() {
+    lenv* env = calloc(1, sizeof(lenv));
+    env->count = 0;
+    env->syms = NULL;
+    return env;
+}
+void lenv_delete(lenv* env) {
+    for(int i = 0; i < env->count; i++) {
+        lval_delete(env->syms[i]->lval);
+        free(env->syms[i]->sym);
+        free(env->syms[i]);
+    }
+    free(env->syms);
+    free(env);
+}
+
+int lenv_compare_symtabs(const void *lhs, const void *rhs) {
+    const struct symtab* l = *(const struct symtab**)lhs;
+    const struct symtab* r = *(const struct symtab**)rhs;
+    
+    return strcmp(l->sym, r->sym);
+}
+
+void lenv_sort(lenv* env) {
+    qsort(env->syms, env->count, sizeof(symtab*), lenv_compare_symtabs);
+}
+
+symtab* lenv_search(lenv* env, char* sym) {
+    if (env->count == 0) {
+        return NULL;
+    }
+    symtab* searchElem = symtab_new(sym, NULL);
+    
+    symtab** searchComp = calloc(1, sizeof(symtab*));
+    searchComp[0] = searchElem;
+    
+    symtab** result = bsearch(searchComp, env->syms, env->count, sizeof(symtab*), lenv_compare_symtabs);
+    
+    free(searchComp);
+    symtab_delete(searchElem);
+    
+    if (result == NULL) {
+        return NULL;
+    }
+    return *result;
+}
+
+lval* lenv_get(lenv* env, lval* sym) {
+    LASSERT(sym, sym->type == LVAL_SYM, LERR_BAD_OP, "Expected symbol");
+    
+    symtab* result = lenv_search(env, sym->data.sym);
+    return result != NULL ? lval_copy(result->lval) : lval_err(LERR_BAD_SYM);
+}
+
+void lenv_put(lenv* env, lval* key, lval* val) {
+    symtab* result = lenv_search(env, key->data.sym);
+    if (result != NULL) {
+        lval_delete(result->lval);
+        result->lval = lval_copy(val);
+        
+        lenv_sort(env);
+        return;
+    }
+    
+    env->count ++;
+    
+    env->syms = realloc(env->syms, sizeof(symtab*) * env->count);
+    
+    env->syms[env->count-1] = symtab_new(key->data.sym, val);
+    
+    lenv_sort(env);
+}
+
+symtab* symtab_new(char* sym, lval* lval) {
+    symtab* new = calloc(1, sizeof(symtab));
+    new->lval = lval == NULL ? NULL : lval_copy(lval);
+    new->sym = strdup(sym);
+    return new;
+}
+void symtab_delete(symtab* symtab) {
+    if (symtab->lval != NULL) {
+        lval_delete(symtab->lval);
+    }
+    free(symtab->sym);
+    free(symtab);
+}