Implement 5.52 translate Scheme to C

shared/scm2c/env.c

@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "env.h"
+#include "primitives.h"
+
+datum* define_variable(const char *var, datum *value, environment *env) {
+    if (env->first_mapping == NULL) {
+        env->first_mapping = new_mapping(var, value);
+        return NULL;
+    }
+
+    mapping* m = env->first_mapping;
+    while (1) {
+        if (strcmp(var, m->variable) == 0) {
+            m->value = value;
+        }
+        if (m->next) {
+            m = m->next;
+        } else {
+            break;
+        }
+    }
+
+    m->next = new_mapping(var, value);
+    return NULL;
+}
+
+datum* lookup_variable_value(char* var, environment* env) {
+    environment* e = env;
+    mapping* m;
+
+    while (e) {
+        m = e->first_mapping;
+        while (m) {
+            if (strcmp(var, m->variable) == 0) {
+                return m->value;
+            }
+            m = m->next;
+        }
+        e = e->outer_env;
+    }
+
+    printf("UNDEFINED VARIABLE %s", var);
+    exit(-1);
+}
+
+datum* make_compiled_proc(void* entry, environment* e) {
+    datum* r = malloc(sizeof(datum));
+    if (!r) exit(-1);
+    r->type = datum_type_compiled_proc;
+    r->compiled_procedure_entry = entry;
+    r->env = e;
+    return r;
+}
+
+environment* extend_environment(const char **args, datum *argl, environment* outer_env) {
+    environment* env = malloc(sizeof(environment));
+    if (!env) exit(-1);
+    env->first_mapping = NULL;
+    env->outer_env = outer_env;
+
+    size_t i = 0;
+    while (argl && args[i]) {
+        define_variable(args[i], argl, env);
+        i += 1;
+        argl = argl->next;
+    }
+
+    return env;
+}
+
+environment* get_global_environment(void) {
+    environment* env = malloc(sizeof(environment));
+    if (!env) exit(-1);
+    env->first_mapping = NULL;
+    env->outer_env = NULL;
+    define_variable("+", const_primitive_proc(&add), env);
+    define_variable("-", const_primitive_proc(&sub), env);
+    define_variable("*", const_primitive_proc(&mul), env);
+    define_variable("=", const_primitive_proc(&eq), env);
+    define_variable("<", const_primitive_proc(&lt), env);
+    define_variable("display", const_primitive_proc(&display), env);
+    define_variable("newline", const_primitive_proc(&newline), env);
+    return env;
+}
+
+mapping* new_mapping(const char* var, datum* value) {
+    mapping* m = malloc(sizeof(mapping));
+    if (!m) exit(-1);
+    m->variable = var;
+    m->value = value;
+    m->next = NULL;
+    return m;
+}
+