go-yaml/path.go

package yaml

import (
	"bytes"
	"fmt"
	"io"
	"strconv"

	"github.com/goccy/go-yaml/ast"
	"github.com/goccy/go-yaml/internal/errors"
	"github.com/goccy/go-yaml/parser"
	"github.com/goccy/go-yaml/printer"
	"golang.org/x/xerrors"
)

var (
	ErrInvalidQuery      = xerrors.New("invalid query")
	ErrInvalidPath       = xerrors.New("invalid path instance")
	ErrInvalidPathString = xerrors.New("invalid path string")
)

// PathString create Path from string
//
// YAMLPath rule
// $     : the root object/element
// .     : child operator
// ..    : recursive descent
// [num] : object/element of array by number
// [*]   : all objects/elements for array.
func PathString(s string) (*Path, error) {
	buf := []rune(s)
	length := len(buf)
	cursor := 0
	builder := &PathBuilder{}
	for cursor < length {
		c := buf[cursor]
		switch c {
		case '$':
			builder = builder.Root()
			cursor++
		case '.':
			b, c, err := parsePathDot(builder, buf, cursor)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to parse path of dot")
			}
			builder = b
			cursor = c
		case '[':
			b, c, err := parsePathIndex(builder, buf, cursor)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to parse path of index")
			}
			builder = b
			cursor = c
		default:
			return nil, errors.Wrapf(ErrInvalidPathString, "invalid path at %d", cursor)
		}
	}
	return builder.Build(), nil
}

func parsePathRecursive(b *PathBuilder, buf []rune, cursor int) (*PathBuilder, int, error) {
	length := len(buf)
	cursor += 2 // skip .. characters
	start := cursor
	for ; cursor < length; cursor++ {
		c := buf[cursor]
		switch c {
		case '$':
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "specified '$' after '..' character")
		case '*':
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "specified '*' after '..' character")
		case '.', '[':
			goto end
		case ']':
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "specified ']' after '..' character")
		}
	}
end:
	if start == cursor {
		return nil, 0, errors.Wrapf(ErrInvalidPathString, "not found recursive selector")
	}
	return b.Recursive(string(buf[start:cursor])), cursor, nil
}

func parsePathDot(b *PathBuilder, buf []rune, cursor int) (*PathBuilder, int, error) {
	length := len(buf)
	if cursor+1 < length && buf[cursor+1] == '.' {
		b, c, err := parsePathRecursive(b, buf, cursor)
		if err != nil {
			return nil, 0, errors.Wrapf(err, "failed to parse path of recursive")
		}
		return b, c, nil
	}
	cursor++ // skip . character
	start := cursor
	for ; cursor < length; cursor++ {
		c := buf[cursor]
		switch c {
		case '$':
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "specified '$' after '.' character")
		case '*':
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "specified '*' after '.' character")
		case '.', '[':
			goto end
		case ']':
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "specified ']' after '.' character")
		}
	}
end:
	if start == cursor {
		return nil, 0, errors.Wrapf(ErrInvalidPathString, "not found child selector")
	}
	return b.Child(string(buf[start:cursor])), cursor, nil
}

func parsePathIndex(b *PathBuilder, buf []rune, cursor int) (*PathBuilder, int, error) {
	length := len(buf)
	cursor++ // skip '[' character
	if length <= cursor {
		return nil, 0, errors.Wrapf(ErrInvalidPathString, "unexpected end of YAML Path")
	}
	c := buf[cursor]
	switch c {
	case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '*':
		start := cursor
		cursor++
		for ; cursor < length; cursor++ {
			c := buf[cursor]
			switch c {
			case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
				continue
			}
			break
		}
		if buf[cursor] != ']' {
			return nil, 0, errors.Wrapf(ErrInvalidPathString, "invalid character %s at %d", string(buf[cursor]), cursor)
		}
		numOrAll := string(buf[start:cursor])
		if numOrAll == "*" {
			return b.IndexAll(), cursor + 1, nil
		}
		num, err := strconv.ParseInt(numOrAll, 10, 64)
		if err != nil {
			return nil, 0, errors.Wrapf(err, "failed to parse number")
		}
		return b.Index(uint(num)), cursor + 1, nil
	}
	return nil, 0, errors.Wrapf(ErrInvalidPathString, "invalid character %s at %d", c, cursor)
}

// Path represent YAMLPath ( like a JSONPath ).
type Path struct {
	node pathNode
}

// String path to text.
func (p *Path) String() string {
	return p.node.String()
}

// Read decode from r and set extracted value by YAMLPath to v.
func (p *Path) Read(r io.Reader, v interface{}) error {
	node, err := p.ReadNode(r)
	if err != nil {
		return errors.Wrapf(err, "failed to read node")
	}
	if err := Unmarshal([]byte(node.String()), v); err != nil {
		return errors.Wrapf(err, "failed to unmarshal")
	}
	return nil
}

// ReadNode create AST from r and extract node by YAMLPath.
func (p *Path) ReadNode(r io.Reader) (ast.Node, error) {
	if p.node == nil {
		return nil, ErrInvalidPath
	}
	var buf bytes.Buffer
	if _, err := io.Copy(&buf, r); err != nil {
		return nil, errors.Wrapf(err, "failed to copy from reader")
	}
	f, err := parser.ParseBytes(buf.Bytes(), 0)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to parse yaml")
	}
	node, err := p.FilterFile(f)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to filter from ast.File")
	}
	return node, nil
}

// Filter filter from target by YAMLPath and set it to v.
func (p *Path) Filter(target, v interface{}) error {
	b, err := Marshal(target)
	if err != nil {
		return errors.Wrapf(err, "failed to marshal target value")
	}
	if err := p.Read(bytes.NewBuffer(b), v); err != nil {
		return errors.Wrapf(err, "failed to read")
	}
	return nil
}

// FilterFile filter from ast.File by YAMLPath.
func (p *Path) FilterFile(f *ast.File) (ast.Node, error) {
	for _, doc := range f.Docs {
		node, err := p.FilterNode(doc.Body)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to filter node by path ( %s )", p.node)
		}
		if node != nil {
			return node, nil
		}
	}
	return nil, nil
}

// FilterNode filter from node by YAMLPath.
func (p *Path) FilterNode(node ast.Node) (ast.Node, error) {
	n, err := p.node.filter(node)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to filter node by path ( %s )", p.node)
	}
	return n, nil
}

// AnnotateSource add annotation to passed source ( see section 5.1 in README.md ).
func (p *Path) AnnotateSource(source []byte, colored bool) ([]byte, error) {
	file, err := parser.ParseBytes([]byte(source), 0)
	if err != nil {
		return nil, err
	}
	node, err := p.FilterFile(file)
	if err != nil {
		return nil, err
	}
	var pp printer.Printer
	return []byte(pp.PrintErrorToken(node.GetToken(), colored)), nil
}

// PathBuilder represent builder for YAMLPath.
type PathBuilder struct {
	root *rootNode
	node pathNode
}

// Root add '$' to current path.
func (b *PathBuilder) Root() *PathBuilder {
	root := newRootNode()
	return &PathBuilder{root: root, node: root}
}

// IndexAll add '[*]' to current path.
func (b *PathBuilder) IndexAll() *PathBuilder {
	b.node = b.node.chain(newIndexAllNode())
	return b
}

// Recursive add '..selector' to current path.
func (b *PathBuilder) Recursive(selector string) *PathBuilder {
	b.node = b.node.chain(newRecursiveNode(selector))
	return b
}

// Child add '.name' to current path.
func (b *PathBuilder) Child(name string) *PathBuilder {
	b.node = b.node.chain(newSelectorNode(name))
	return b
}

// Index add '[idx]' to current path.
func (b *PathBuilder) Index(idx uint) *PathBuilder {
	b.node = b.node.chain(newIndexNode(idx))
	return b
}

// Build build YAMLPath.
func (b *PathBuilder) Build() *Path {
	return &Path{node: b.root}
}

type pathNode interface {
	fmt.Stringer
	chain(pathNode) pathNode
	filter(ast.Node) (ast.Node, error)
}

type basePathNode struct {
	child pathNode
}

func (n *basePathNode) chain(node pathNode) pathNode {
	n.child = node
	return node
}

type rootNode struct {
	*basePathNode
}

func newRootNode() *rootNode {
	return &rootNode{basePathNode: &basePathNode{}}
}

func (n *rootNode) String() string {
	s := "$"
	if n.child != nil {
		s += n.child.String()
	}
	return s
}

func (n *rootNode) filter(node ast.Node) (ast.Node, error) {
	if n.child == nil {
		return nil, nil
	}
	filtered, err := n.child.filter(node)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to filter")
	}
	return filtered, nil
}

type selectorNode struct {
	*basePathNode
	selector string
}

func newSelectorNode(selector string) *selectorNode {
	return &selectorNode{
		basePathNode: &basePathNode{},
		selector:     selector,
	}
}

func (n *selectorNode) filter(node ast.Node) (ast.Node, error) {
	switch node.Type() {
	case ast.MappingType:
		for _, value := range node.(*ast.MappingNode).Values {
			key := value.Key.GetToken().Value
			if key == n.selector {
				if n.child == nil {
					return value.Value, nil
				}
				filtered, err := n.child.filter(value.Value)
				if err != nil {
					return nil, errors.Wrapf(err, "failed to filter")
				}
				return filtered, nil
			}
		}
	case ast.MappingValueType:
		value := node.(*ast.MappingValueNode)
		key := value.Key.GetToken().Value
		if key == n.selector {
			if n.child == nil {
				return value.Value, nil
			}
			filtered, err := n.child.filter(value.Value)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to filter")
			}
			return filtered, nil
		}
	default:
		return nil, errors.Wrapf(ErrInvalidQuery, "expected node type is map or map value. but got %s", node.Type())
	}
	return nil, nil
}

func (n *selectorNode) String() string {
	s := fmt.Sprintf(".%s", n.selector)
	if n.child != nil {
		s += n.child.String()
	}
	return s
}

type indexNode struct {
	*basePathNode
	selector uint
}

func newIndexNode(selector uint) *indexNode {
	return &indexNode{
		basePathNode: &basePathNode{},
		selector:     selector,
	}
}

func (n *indexNode) filter(node ast.Node) (ast.Node, error) {
	if node.Type() != ast.SequenceType {
		return nil, errors.Wrapf(ErrInvalidQuery, "expected sequence type node. but got %s", node.Type())
	}
	sequence := node.(*ast.SequenceNode)
	if n.selector >= uint(len(sequence.Values)) {
		return nil, errors.Wrapf(ErrInvalidQuery, "expected index is %d. but got sequences has %d items", n.selector, sequence.Values)
	}
	value := sequence.Values[n.selector]
	if n.child == nil {
		return value, nil
	}
	filtered, err := n.child.filter(value)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to filter")
	}
	return filtered, nil
}

func (n *indexNode) String() string {
	s := fmt.Sprintf("[%d]", n.selector)
	if n.child != nil {
		s += n.child.String()
	}
	return s
}

type indexAllNode struct {
	*basePathNode
}

func newIndexAllNode() *indexAllNode {
	return &indexAllNode{
		basePathNode: &basePathNode{},
	}
}

func (n *indexAllNode) String() string {
	s := "[*]"
	if n.child != nil {
		s += n.child.String()
	}
	return s
}

func (n *indexAllNode) filter(node ast.Node) (ast.Node, error) {
	if node.Type() != ast.SequenceType {
		return nil, errors.Wrapf(ErrInvalidQuery, "expected sequence type node. but got %s", node.Type())
	}
	sequence := node.(*ast.SequenceNode)
	if n.child == nil {
		return sequence, nil
	}
	out := *sequence
	out.Values = []ast.Node{}
	for _, value := range sequence.Values {
		filtered, err := n.child.filter(value)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to filter")
		}
		out.Values = append(out.Values, filtered)
	}
	return &out, nil
}

type recursiveNode struct {
	*basePathNode
	selector string
}

func newRecursiveNode(selector string) *recursiveNode {
	return &recursiveNode{
		basePathNode: &basePathNode{},
		selector:     selector,
	}
}

func (n *recursiveNode) String() string {
	s := fmt.Sprintf("..%s", n.selector)
	if n.child != nil {
		s += n.child.String()
	}
	return s
}

func (n *recursiveNode) filterNode(node ast.Node) (*ast.SequenceNode, error) {
	sequence := &ast.SequenceNode{}
	switch typedNode := node.(type) {
	case *ast.MappingNode:
		for _, value := range typedNode.Values {
			seq, err := n.filterNode(value)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to filter")
			}
			sequence.Values = append(sequence.Values, seq.Values...)
		}
	case *ast.MappingValueNode:
		key := typedNode.Key.GetToken().Value
		if n.selector == key {
			sequence.Values = append(sequence.Values, typedNode.Value)
		}
		seq, err := n.filterNode(typedNode.Value)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to filter")
		}
		sequence.Values = append(sequence.Values, seq.Values...)
	case *ast.SequenceNode:
		for _, value := range typedNode.Values {
			seq, err := n.filterNode(value)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to filter")
			}
			sequence.Values = append(sequence.Values, seq.Values...)
		}
	}
	return sequence, nil
}

func (n *recursiveNode) filter(node ast.Node) (ast.Node, error) {
	sequence, err := n.filterNode(node)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to filter")
	}
	sequence.Start = node.GetToken()
	return sequence, nil
}