mirror of
https://github.com/google/go-jsonnet.git
synced 2025-08-07 23:07:14 +02:00
121 lines
3.0 KiB
Go
121 lines
3.0 KiB
Go
/*
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Copyright 2017 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package jsonnet
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import (
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"errors"
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"fmt"
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"runtime/debug"
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"github.com/google/go-jsonnet/ast"
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"github.com/google/go-jsonnet/parser"
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)
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// Note: There are no garbage collection params because we're using the native
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// Go garbage collector.
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// TODO(sbarzowski) prepare API that maps 1-1 to libjsonnet api
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// VM is the core interpreter and is the touchpoint used to parse and execute
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// Jsonnet.
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type VM struct {
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MaxStack int
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MaxTrace int // The number of lines of stack trace to display (0 for all of them).
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ext vmExtMap
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importer Importer
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ef ErrorFormatter
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}
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// TODO(sbarzowski) actually support these
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// External variable (or code) provided before execution
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type vmExt struct {
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value string // what is it?
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isCode bool // what is it?
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}
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type vmExtMap map[string]vmExt
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// MakeVM creates a new VM with default parameters.
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func MakeVM() *VM {
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return &VM{
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MaxStack: 500,
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MaxTrace: 20,
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ext: make(vmExtMap),
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ef: ErrorFormatter{},
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}
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}
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// ExtVar binds a Jsonnet external var to the given value.
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func (vm *VM) ExtVar(key string, val string) {
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vm.ext[key] = vmExt{value: val, isCode: false}
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}
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// ExtCode binds a Jsonnet external code var to the given value.
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func (vm *VM) ExtCode(key string, val string) {
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vm.ext[key] = vmExt{value: val, isCode: true}
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}
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func (vm *VM) evaluateSnippet(filename string, snippet string) (string, error) {
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node, err := snippetToAST(filename, snippet)
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if err != nil {
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return "", err
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}
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output, err := evaluate(node, vm.ext, vm.MaxStack, &FileImporter{})
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if err != nil {
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return "", err
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}
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return output, nil
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}
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// EvaluateSnippet evaluates a string containing Jsonnet code, return a JSON
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// string.
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//
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// The filename parameter is only used for error messages.
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func (vm *VM) EvaluateSnippet(filename string, snippet string) (json string, formattedErr error) {
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defer func() {
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if r := recover(); r != nil {
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formattedErr = errors.New(vm.ef.format(fmt.Errorf("(CRASH) %v\n%s", r, debug.Stack())))
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}
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}()
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json, err := vm.evaluateSnippet(filename, snippet)
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if err != nil {
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return "", errors.New(vm.ef.format(err))
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}
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return json, nil
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}
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func snippetToAST(filename string, snippet string) (ast.Node, error) {
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tokens, err := parser.Lex(filename, snippet)
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if err != nil {
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return nil, err
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}
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node, err := parser.Parse(tokens)
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if err != nil {
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return nil, err
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}
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// fmt.Println(ast.(dumpable).dump())
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err = desugarFile(&node)
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if err != nil {
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return nil, err
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}
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err = analyze(node)
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if err != nil {
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return nil, err
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}
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return node, nil
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}
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