Done with the book! Added hash maps and the puts builtin.

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

pkg/evaluator/builtins.go

@@ -1,12 +1,21 @@
 package evaluator
 
 import (
+	"fmt"
 	"os"
 
 	"code.jmug.me/jmug/interpreter-in-go/pkg/object"
 )
 
 var builtins = map[string]*object.Builtin{
+	"puts": {
+		Fn: func(args ...object.Object) object.Object {
+			for _, arg := range args {
+				fmt.Println(arg.Inspect())
+			}
+			return _NULL
+		},
+	},
 	"len": {
 		Fn: func(args ...object.Object) object.Object {
 			if len(args) != 1 {

pkg/evaluator/evaluator.go

@@ -91,6 +91,8 @@ func Eval(node ast.Node, env *object.Environment) object.Object {
 			return index
 		}
 		return evalIndexExpression(left, index)
+	case *ast.HashLiteral:
+		return evalHashLiteral(node, env)
 	}
 	return nil
 }
@@ -251,6 +253,8 @@ func evalIndexExpression(left, index object.Object) object.Object {
 	switch {
 	case left.Type() == object.ARRAY_OBJ && index.Type() == object.INTEGER_OBJ:
 		return evalArrayIndexExpression(left, index)
+	case left.Type() == object.HASH_OBJ:
+		return evalHashIndexExpression(left, index)
 	default:
 		return newError("index operator not supported: %s", left.Type())
 	}
@@ -265,6 +269,40 @@ func evalArrayIndexExpression(arrayObj, indexObj object.Object) object.Object {
 	return array[index]
 }
 
+func evalHashIndexExpression(hashObj, index object.Object) object.Object {
+	hash := hashObj.(*object.Hash)
+	hashable, okHash := index.(object.Hashable)
+	if !okHash {
+		return newError("unusable as hash key: %s", index.Type())
+	}
+	pair, okPair := hash.Pairs[hashable.HashKey()]
+	if !okPair {
+		return _NULL
+	}
+	return pair.Value
+}
+
+func evalHashLiteral(hash *ast.HashLiteral, env *object.Environment) object.Object {
+	pairs := map[object.HashKey]object.HashPair{}
+	for ke, ve := range hash.Pairs {
+		k := Eval(ke, env)
+		if isError(k) {
+			return k
+		}
+		hashable, ok := k.(object.Hashable)
+		if !ok {
+			return newError("unusable as hash key: %s", k.Type())
+		}
+		v := Eval(ve, env)
+		if isError(v) {
+			return v
+		}
+		hashKey := hashable.HashKey()
+		pairs[hashKey] = object.HashPair{Key: k, Value: v}
+	}
+	return &object.Hash{Pairs: pairs}
+}
+
 func applyFunction(fnObj object.Object, args []object.Object) object.Object {
 	switch fn := fnObj.(type) {
 	case *object.Function:

pkg/evaluator/evaluator_test.go

@@ -190,6 +190,10 @@ if (10 > 1) {
 			`"Hello" - "World"`,
 			"unknown operator: STRING - STRING",
 		},
+		{
+			`{"name": "Monkey"}[fn(x) { x }];`,
+			"unusable as hash key: FUNCTION",
+		},
 	}
 
 	for _, tt := range tests {
@@ -406,6 +410,92 @@ func TestArrayIndexExpressions(t *testing.T) {
 	}
 }
 
+func TestHashLiterals(t *testing.T) {
+	input := `let two = "two";
+    {
+        "one": 10 - 9,
+        two: 1 + 1,
+        "thr" + "ee": 6 / 2,
+        4: 4,
+        true: 5,
+        false: 6
+    }`
+
+	evaluated := testEval(input)
+	result, ok := evaluated.(*object.Hash)
+	if !ok {
+		t.Fatalf("Eval didn't return Hash. got=%T (%+v)", evaluated, evaluated)
+	}
+
+	expected := map[object.HashKey]int64{
+		(&object.String{Value: "one"}).HashKey():   1,
+		(&object.String{Value: "two"}).HashKey():   2,
+		(&object.String{Value: "three"}).HashKey(): 3,
+		(&object.Integer{Value: 4}).HashKey():      4,
+		_TRUE.HashKey():                            5,
+		_FALSE.HashKey():                           6,
+	}
+
+	if len(result.Pairs) != len(expected) {
+		t.Fatalf("Hash has wrong num of pairs. got=%d", len(result.Pairs))
+	}
+
+	for expectedKey, expectedValue := range expected {
+		pair, ok := result.Pairs[expectedKey]
+		if !ok {
+			t.Errorf("no pair for given key in Pairs")
+		}
+
+		testIntegerObject(t, pair.Value, expectedValue)
+	}
+}
+
+func TestHashIndexExpressions(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected interface{}
+	}{
+		{
+			`{"foo": 5}["foo"]`,
+			5,
+		},
+		{
+			`{"foo": 5}["bar"]`,
+			nil,
+		},
+		{
+			`let key = "foo"; {"foo": 5}[key]`,
+			5,
+		},
+		{
+			`{}["foo"]`,
+			nil,
+		},
+		{
+			`{5: 5}[5]`,
+			5,
+		},
+		{
+			`{true: 5}[true]`,
+			5,
+		},
+		{
+			`{false: 5}[false]`,
+			5,
+		},
+	}
+
+	for _, tt := range tests {
+		evaluated := testEval(tt.input)
+		integer, ok := tt.expected.(int)
+		if ok {
+			testIntegerObject(t, evaluated, int64(integer))
+		} else {
+			testNullObject(t, evaluated)
+		}
+	}
+}
+
 func testNullObject(t *testing.T, obj object.Object) bool {
 	if obj != _NULL {
 		t.Errorf("object is not NULL. got=%T (%+v)", obj, obj)