Finish subtask 1

src/ast_interpreter.c

@@ -97,13 +97,13 @@ Value env_get ( ASTInterpreterState * state, Str name ) {
   }
   // fprintf ( stderr, "Variable with name %.*s does not exist.\n", (int) name . len, name . str );
   // exit ( 1 );
-  return (Value) { .kind = VALUE_NULL };
-  // env = state -> current_env;
-  // env = env ? env : & state -> global_env;
-  // entry = (EnvironmentEntry*) malloc ( sizeof (EnvironmentEntry) );
-  // (*entry) = (EnvironmentEntry) {.name = name, .value = (Value) { .kind = VALUE_NULL }, .next = env -> start };
-  // env -> start = entry;
-  // return entry -> value;
+  // return (Value) { .kind = VALUE_NULL };
+  env = state -> current_env;
+  env = env ? env : & state -> global_env;
+  entry = (EnvironmentEntry*) malloc ( sizeof (EnvironmentEntry) );
+  (*entry) = (EnvironmentEntry) {.name = name, .value = (Value) { .kind = VALUE_NULL }, .next = env -> start };
+  env -> start = entry;
+  return entry -> value;
 }
 void * heap_alloc ( Heap * heap, size_t len, size_t align ) {
@@ -157,6 +157,29 @@ void state_destroy ( ASTInterpreterState * state ) {
   }
 }
+Value function_call ( ASTInterpreterState * state, Value function, bool is_function, Ast ** arguments, size_t argc ) {
+  Value * values = (Value *) malloc ( argc * sizeof (Value) );
+  for ( size_t i = 0; i < argc; ++i )
+    values [ i ] = evaluate ( state, arguments [ i ] );
+  if ( is_function ) {
+    if ( function . kind != VALUE_FUNCTION ) {
+      fprintf ( stderr, "Invalid calee.\n" );
+      exit ( 4 );
+    }
+    Environment * tmp = state -> current_env;
+    state -> current_env = NULL;
+    env_push ( state );
+    env_def ( state, STR ("this"), (Value) { .kind = VALUE_NULL} );
+    for ( size_t i = 0; i < argc; ++i )
+      env_def ( state, function . function -> parameters [ i ], values [ i ] );
+    Value ret = evaluate ( state, function . function -> body );
+    env_pop ( state );
+    state -> current_env = tmp;
+    return ret;
+  }
+  return (Value) { .kind = VALUE_NULL };
+}
+
 void print_value ( Value value ) {
   switch ( value . kind ) {
     case VALUE_INTEGER:
@@ -171,6 +194,9 @@ void print_value ( Value value ) {
     case VALUE_NULL:
       printf ( "null" );
       break;
+    case VALUE_FUNCTION:
+      printf ( "function" );
+      break;
   }
 }
@@ -282,6 +308,13 @@ Value evaluate ( ASTInterpreterState * state, Ast * ast ) {
       }
       return (Value) { .kind = VALUE_NULL };
     }
+    case AST_FUNCTION:
+      return (Value) { .kind = VALUE_FUNCTION, .function = (AstFunction*) ast };
+    case AST_FUNCTION_CALL: {
+      AstFunctionCall * callAst = (AstFunctionCall*) ast;
+      Value function = evaluate ( state, callAst -> function );
+      return function_call ( state, function, true, callAst -> arguments, callAst -> argument_cnt ); 
+    }
   }
   return (Value) { .kind = VALUE_NULL };
 }

src/ast_interpreter.h

@@ -3,7 +3,8 @@
 typedef enum {
   VALUE_INTEGER,
   VALUE_BOOLEAN,
-  VALUE_NULL
+  VALUE_NULL,
+  VALUE_FUNCTION
 } ValueType;
 typedef struct Heap {
@@ -17,6 +18,7 @@ typedef struct Value {
   union {
     i32 integer;
     bool boolean;
+    AstFunction * function;
   };
 } Value;
@@ -50,6 +52,7 @@ void heap_destroy ( Heap * heap );
 void state_init ( ASTInterpreterState * state, Heap * heap );
 void state_destroy ( ASTInterpreterState * state );
+Value function_call ( ASTInterpreterState * state, Value function, bool is_function, Ast ** arguments, size_t argc );
 void print_value ( Value value );
 void fml_print ( Str format, Value * args, size_t argc );
 Value evaluate ( ASTInterpreterState * state, Ast * ast );
\ No newline at end of file