First end-to-end test (addition of numbers)

Author: sparkprime

.gitignore

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+*~

desugarer.go

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+/*
+Copyright 2016 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package jsonnet
+
+func desugar(ast astNode, objLevel int) (astNode, error) {
+	return ast, nil
+}
+
+func desugarFile(ast astNode) (astNode, error) {
+	ast, err := desugar(ast, 0)
+	if err != nil {
+		return nil, err
+	}
+	// TODO(dcunnin): wrap in std local
+	return ast, nil
+}

desugarer_test.go

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+/*
+Copyright 2016 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package jsonnet

interpreter.go

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+/*
+Copyright 2016 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package jsonnet
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+)
+
+// Misc top-level stuff
+
+type vmExt struct {
+	value  string
+	isCode bool
+}
+
+type vmExtMap map[string]vmExt
+
+type RuntimeError struct {
+	StackTrace []traceFrame
+	Msg        string
+}
+
+func makeRuntimeError(msg string) RuntimeError {
+	return RuntimeError{
+		Msg: msg,
+	}
+}
+
+func (err RuntimeError) Error() string {
+	// TODO(dcunnin): Include stacktrace.
+	return err.Msg
+}
+
+// Values and state
+
+type bindingFrame map[*identifier]thunk
+
+type value interface {
+}
+
+type valueString struct {
+	value string
+}
+
+func makeValueString(v string) *valueString {
+	return &valueString{value: v}
+}
+
+type valueBoolean struct {
+	value bool
+}
+
+func makeValueBoolean(v bool) *valueBoolean {
+	return &valueBoolean{value: v}
+}
+
+type valueNumber struct {
+	value float64
+}
+
+func makeValueNumber(v float64) *valueNumber {
+	return &valueNumber{value: v}
+}
+
+// TODO(dcunnin): Maybe intern values null, true, and false?
+type valueNull struct {
+}
+
+func makeValueNull() *valueNull {
+	return &valueNull{}
+}
+
+type thunk struct {
+	Content  value // nil if not filled
+	Name     *identifier
+	UpValues bindingFrame
+	Self     value
+	Offset   int
+	Body     astNode
+}
+
+func makeThunk(name *identifier, self *value, offset int, body astNode) *thunk {
+	return &thunk{
+		Name:   name,
+		Self:   self,
+		Offset: offset,
+		Body:   body,
+	}
+}
+
+func (t *thunk) fill(v value) {
+	t.Content = v
+	t.Self = nil
+	t.UpValues = make(bindingFrame) // clear the map
+}
+
+type valueArray struct {
+	Elements []thunk
+}
+
+func makeValueArray(elements []thunk) *valueArray {
+	return &valueArray{
+		Elements: elements,
+	}
+}
+
+// TODO(dcunnin): SimpleObject
+// TODO(dcunnin): ExtendedObject
+// TODO(dcunnin): ComprehensionObject
+// TODO(dcunnin): Closure
+
+// The stack
+
+type traceFrame struct {
+	Loc  LocationRange
+	Name string
+}
+
+type callFrame struct {
+	bindings bindingFrame
+}
+
+type callStack struct {
+	Calls int
+	Limit int
+	Stack []callFrame
+}
+
+func makeCallStack(limit int) callStack {
+	return callStack{
+		Calls: 0,
+		Limit: limit,
+	}
+}
+
+// TODO(dcunnin): Add import callbacks.
+// TODO(dcunnin): Add string output.
+// TODO(dcunnin): Add multi output.
+
+type interpreter struct {
+	Stack        callStack
+	ExternalVars vmExtMap
+}
+
+func (this interpreter) execute(ast_ astNode) (value, error) {
+	// TODO(dcunnin): All the other cases...
+	switch ast := ast_.(type) {
+	case *astBinary:
+		// TODO(dcunnin): Assume it's + on numbers for now
+		leftVal, err := this.execute(ast.left)
+		if err != nil {
+			return nil, err
+		}
+		leftNum := leftVal.(*valueNumber).value
+		rightVal, err := this.execute(ast.right)
+		if err != nil {
+			return nil, err
+		}
+		rightNum := rightVal.(*valueNumber).value
+		return makeValueNumber(leftNum + rightNum), nil
+	case *astLiteralNull:
+		return makeValueNull(), nil
+	case *astLiteralBoolean:
+		return makeValueBoolean(ast.value), nil
+	case *astLiteralNumber:
+		return makeValueNumber(ast.value), nil
+	default:
+		return nil, makeRuntimeError("Executing this AST type not implemented yet.")
+	}
+}
+
+func unparseNumber(v float64) string {
+	if v == math.Floor(v) {
+		return fmt.Sprintf("%.0f", v)
+	} else {
+		// See "What Every Computer Scientist Should Know About Floating-Point Arithmetic"
+		// Theorem 15
+		// http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
+		return fmt.Sprintf("%.17g", v)
+	}
+}
+
+func (this interpreter) manifestJson(
+	v_ value, multiline bool, indent string, buf *bytes.Buffer) error {
+	// TODO(dcunnin): All the other types...
+	switch v := v_.(type) {
+	case *valueBoolean:
+		if v.value {
+			buf.WriteString("true")
+		} else {
+			buf.WriteString("false")
+		}
+	case *valueNull:
+		buf.WriteString("null")
+	case *valueNumber:
+		buf.WriteString(unparseNumber(v.value))
+	default:
+		return makeRuntimeError("Manifesting this value not implemented yet.")
+	}
+	return nil
+}
+
+func execute(ast astNode, ext vmExtMap, maxStack int) (string, error) {
+	theInterpreter := interpreter{
+		Stack:        makeCallStack(maxStack),
+		ExternalVars: ext,
+	}
+	result, err := theInterpreter.execute(ast)
+	if err != nil {
+		return "", err
+	}
+	var buffer bytes.Buffer
+	err = theInterpreter.manifestJson(result, true, "", &buffer)
+	if err != nil {
+		return "", err
+	}
+	return buffer.String(), nil
+}

interpreter_test.go

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+/*
+Copyright 2016 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package jsonnet

main.go

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+/*
+Copyright 2016 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package jsonnet
+
+// Note: There are no garbage collection params because we're using the native Go garbage collector.
+type Vm struct {
+	maxStack int
+	maxTrace int
+	ext      vmExtMap
+}
+
+func MakeVm() *Vm {
+	return &Vm{
+		maxStack: 500,
+		maxTrace: 20,
+	}
+}
+
+func (vm *Vm) ExtVar(key string, val string) {
+	vm.ext[key] = vmExt{value: val, isCode: false}
+}
+
+func (vm *Vm) ExtCode(key string, val string) {
+	vm.ext[key] = vmExt{value: val, isCode: true}
+}
+
+func (vm *Vm) EvaluateSnippet(filename string, snippet string) (string, error) {
+	tokens, err := lex(filename, snippet)
+	if err != nil {
+		return "", err
+	}
+	ast, err := parse(tokens)
+	if err != nil {
+		return "", err
+	}
+	ast, err = desugarFile(ast)
+	output, err := execute(ast, vm.ext, vm.maxStack)
+	if err != nil {
+		return "", err
+	}
+	return output, nil
+}