parser/printer.go - third_party/blueprint - Git at Google

 // Copyright 2014 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 parser

 import (
 	"fmt"
 	"strconv"
 	"strings"
 	"text/scanner"
 	"unicode"
 )

 var noPos scanner.Position

 type printer struct {
 	defs     []Definition
 	comments []*CommentGroup

 	curComment int

 	pos scanner.Position

 	pendingSpace   bool
 	pendingNewline int

 	output []byte

 	indentList []int
 	wsBuf      []byte

 	skippedComments []*CommentGroup
 }

 func newPrinter(file *File) *printer {
 	return &printer{
 		defs:       file.Defs,
 		comments:   file.Comments,
 		indentList: []int{0},

 		// pendingNewLine is initialized to -1 to eat initial spaces if the first token is a comment
 		pendingNewline: -1,

 		pos: scanner.Position{
 			Line: 1,
 		},
 	}
 }

 func Print(file *File) ([]byte, error) {
 	p := newPrinter(file)

 	for _, def := range p.defs {
 		p.printDef(def)
 	}
 	p.flush()
 	return p.output, nil
 }

 func (p *printer) Print() ([]byte, error) {
 	for _, def := range p.defs {
 		p.printDef(def)
 	}
 	p.flush()
 	return p.output, nil
 }

 func (p *printer) printDef(def Definition) {
 	if assignment, ok := def.(*Assignment); ok {
 		p.printAssignment(assignment)
 	} else if module, ok := def.(*Module); ok {
 		p.printModule(module)
 	} else {
 		panic("Unknown definition")
 	}
 }

 func (p *printer) printAssignment(assignment *Assignment) {
 	p.printToken(assignment.Name, assignment.NamePos)
 	p.requestSpace()
 	p.printToken(assignment.Assigner, assignment.EqualsPos)
 	p.requestSpace()
 	p.printExpression(assignment.OrigValue)
 	p.requestNewline()
 }

 func (p *printer) printModule(module *Module) {
 	p.printToken(module.Type, module.TypePos)
 	p.printMap(&module.Map)
 	p.requestDoubleNewline()
 }

 func (p *printer) printExpression(value Expression) {
 	switch v := value.(type) {
 	case *Variable:
 		p.printToken(v.Name, v.NamePos)
 	case *Operator:
 		p.printOperator(v)
 	case *Bool:
 		var s string
 		if v.Value {
 			s = "true"
 		} else {
 			s = "false"
 		}
 		p.printToken(s, v.LiteralPos)
 	case *String:
 		p.printToken(strconv.Quote(v.Value), v.LiteralPos)
 	case *List:
 		p.printList(v.Values, v.LBracePos, v.RBracePos)
 	case *Map:
 		p.printMap(v)
 	default:
 		panic(fmt.Errorf("bad property type: %s", value.Type()))
 	}
 }

 func (p *printer) printList(list []Expression, pos, endPos scanner.Position) {
 	p.requestSpace()
 	p.printToken("[", pos)
 	if len(list) > 1 || pos.Line != endPos.Line {
 		p.requestNewline()
 		p.indent(p.curIndent() + 4)
 		for _, value := range list {
 			p.printExpression(value)
 			p.printToken(",", noPos)
 			p.requestNewline()
 		}
 		p.unindent(endPos)
 	} else {
 		for _, value := range list {
 			p.printExpression(value)
 		}
 	}
 	p.printToken("]", endPos)
 }

 func (p *printer) printMap(m *Map) {
 	p.requestSpace()
 	p.printToken("{", m.LBracePos)
 	if len(m.Properties) > 0 || m.LBracePos.Line != m.RBracePos.Line {
 		p.requestNewline()
 		p.indent(p.curIndent() + 4)
 		for _, prop := range m.Properties {
 			p.printProperty(prop)
 			p.printToken(",", noPos)
 			p.requestNewline()
 		}
 		p.unindent(m.RBracePos)
 	}
 	p.printToken("}", m.RBracePos)
 }

 func (p *printer) printOperator(operator *Operator) {
 	p.printExpression(operator.Args[0])
 	p.requestSpace()
 	p.printToken(string(operator.Operator), operator.OperatorPos)
 	if operator.Args[0].End().Line == operator.Args[1].Pos().Line {
 		p.requestSpace()
 	} else {
 		p.requestNewline()
 	}
 	p.printExpression(operator.Args[1])
 }

 func (p *printer) printProperty(property *Property) {
 	p.printToken(property.Name, property.NamePos)
 	p.printToken(":", property.ColonPos)
 	p.requestSpace()
 	p.printExpression(property.Value)
 }

 // Print a single token, including any necessary comments or whitespace between
 // this token and the previously printed token
 func (p *printer) printToken(s string, pos scanner.Position) {
 	newline := p.pendingNewline != 0

 	if pos == noPos {
 		pos = p.pos
 	}

 	if newline {
 		p.printEndOfLineCommentsBefore(pos)
 		p.requestNewlinesForPos(pos)
 	}

 	p.printInLineCommentsBefore(pos)

 	p.flushSpace()

 	p.output = append(p.output, s...)

 	p.pos = pos
 }

 // Print any in-line (single line /* */) comments that appear _before_ pos
 func (p *printer) printInLineCommentsBefore(pos scanner.Position) {
 	for p.curComment < len(p.comments) && p.comments[p.curComment].Pos().Offset < pos.Offset {
 		c := p.comments[p.curComment]
 		if c.Comments[0].Comment[0][0:2] == "//" || len(c.Comments[0].Comment) > 1 {
 			p.skippedComments = append(p.skippedComments, c)
 		} else {
 			p.printComment(c)
 			p.requestSpace()
 		}
 		p.curComment++
 	}
 }

 // Print any comments, including end of line comments, that appear _before_ the line specified
 // by pos
 func (p *printer) printEndOfLineCommentsBefore(pos scanner.Position) {
 	if len(p.skippedComments) > 0 {
 		for _, c := range p.skippedComments {
 			p.printComment(c)
 		}
 		p._requestNewline()
 		p.skippedComments = nil
 	}
 	for p.curComment < len(p.comments) && p.comments[p.curComment].Pos().Line < pos.Line {
 		c := p.comments[p.curComment]
 		p.printComment(c)
 		p._requestNewline()
 		p.curComment++
 	}
 }

 // Compare the line numbers of the previous and current positions to determine whether extra
 // newlines should be inserted.  A second newline is allowed anywhere requestNewline() is called.
 func (p *printer) requestNewlinesForPos(pos scanner.Position) bool {
 	if pos.Line > p.pos.Line {
 		p._requestNewline()
 		if pos.Line > p.pos.Line+1 {
 			p.pendingNewline = 2
 		}
 		return true
 	}

 	return false
 }

 func (p *printer) requestSpace() {
 	p.pendingSpace = true
 }

 // Ask for a newline to be inserted before the next token, but do not insert any comments.  Used
 // by the comment printers.
 func (p *printer) _requestNewline() {
 	if p.pendingNewline == 0 {
 		p.pendingNewline = 1
 	}
 }

 // Ask for a newline to be inserted before the next token.  Also inserts any end-of line comments
 // for the current line
 func (p *printer) requestNewline() {
 	pos := p.pos
 	pos.Line++
 	p.printEndOfLineCommentsBefore(pos)
 	p._requestNewline()
 }

 // Ask for two newlines to be inserted before the next token.  Also inserts any end-of line comments
 // for the current line
 func (p *printer) requestDoubleNewline() {
 	p.requestNewline()
 	p.pendingNewline = 2
 }

 // Flush any pending whitespace, ignoring pending spaces if there is a pending newline
 func (p *printer) flushSpace() {
 	if p.pendingNewline == 1 {
 		p.output = append(p.output, '\n')
 		p.pad(p.curIndent())
 	} else if p.pendingNewline == 2 {
 		p.output = append(p.output, "\n\n"...)
 		p.pad(p.curIndent())
 	} else if p.pendingSpace == true && p.pendingNewline != -1 {
 		p.output = append(p.output, ' ')
 	}

 	p.pendingSpace = false
 	p.pendingNewline = 0
 }

 // Print a single comment, which may be a multi-line comment
 func (p *printer) printComment(cg *CommentGroup) {
 	for _, comment := range cg.Comments {
 		if !p.requestNewlinesForPos(comment.Pos()) {
 			p.requestSpace()
 		}
 		for i, line := range comment.Comment {
 			line = strings.TrimRightFunc(line, unicode.IsSpace)
 			p.flushSpace()
 			if i != 0 {
 				lineIndent := strings.IndexFunc(line, func(r rune) bool { return !unicode.IsSpace(r) })
 				lineIndent = max(lineIndent, p.curIndent())
 				p.pad(lineIndent - p.curIndent())
 			}
 			p.output = append(p.output, strings.TrimSpace(line)...)
 			if i < len(comment.Comment)-1 {
 				p._requestNewline()
 			}
 		}
 		p.pos = comment.End()
 	}
 }

 // Print any comments that occur after the last token, and a trailing newline
 func (p *printer) flush() {
 	for _, c := range p.skippedComments {
 		if !p.requestNewlinesForPos(c.Pos()) {
 			p.requestSpace()
 		}
 		p.printComment(c)
 	}
 	for p.curComment < len(p.comments) {
 		p.printComment(p.comments[p.curComment])
 		p.curComment++
 	}
 	p.output = append(p.output, '\n')
 }

 // Print whitespace to pad from column l to column max
 func (p *printer) pad(l int) {
 	if l > len(p.wsBuf) {
 		p.wsBuf = make([]byte, l)
 		for i := range p.wsBuf {
 			p.wsBuf[i] = ' '
 		}
 	}
 	p.output = append(p.output, p.wsBuf[0:l]...)
 }

 func (p *printer) indent(i int) {
 	p.indentList = append(p.indentList, i)
 }

 func (p *printer) unindent(pos scanner.Position) {
 	p.printEndOfLineCommentsBefore(pos)
 	p.indentList = p.indentList[0 : len(p.indentList)-1]
 }

 func (p *printer) curIndent() int {
 	return p.indentList[len(p.indentList)-1]
 }

 func max(a, b int) int {
 	if a > b {
 		return a
 	} else {
 		return b
 	}
 }
	// Copyright 2014 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 parser

	import (
	"fmt"
	"strconv"
	"strings"
	"text/scanner"
	"unicode"
	)

	var noPos scanner.Position

	type printer struct {
	defs []Definition
	comments []*CommentGroup

	curComment int

	pos scanner.Position

	pendingSpace bool
	pendingNewline int

	output []byte

	indentList []int
	wsBuf []byte

	skippedComments []*CommentGroup
	}

	func newPrinter(file File) printer {
	return &printer{
	defs: file.Defs,
	comments: file.Comments,
	indentList: []int{0},

	// pendingNewLine is initialized to -1 to eat initial spaces if the first token is a comment
	pendingNewline: -1,

	pos: scanner.Position{
	Line: 1,
	},
	}
	}

	func Print(file *File) ([]byte, error) {
	p := newPrinter(file)

	for _, def := range p.defs {
	p.printDef(def)
	}
	p.flush()
	return p.output, nil
	}

	func (p *printer) Print() ([]byte, error) {
	for _, def := range p.defs {
	p.printDef(def)
	}
	p.flush()
	return p.output, nil
	}

	func (p *printer) printDef(def Definition) {
	if assignment, ok := def.(*Assignment); ok {
	p.printAssignment(assignment)
	} else if module, ok := def.(*Module); ok {
	p.printModule(module)
	} else {
	panic("Unknown definition")
	}
	}

	func (p printer) printAssignment(assignment Assignment) {
	p.printToken(assignment.Name, assignment.NamePos)
	p.requestSpace()
	p.printToken(assignment.Assigner, assignment.EqualsPos)
	p.requestSpace()
	p.printExpression(assignment.OrigValue)
	p.requestNewline()
	}

	func (p printer) printModule(module Module) {
	p.printToken(module.Type, module.TypePos)
	p.printMap(&module.Map)
	p.requestDoubleNewline()
	}

	func (p *printer) printExpression(value Expression) {
	switch v := value.(type) {
	case *Variable:
	p.printToken(v.Name, v.NamePos)
	case *Operator:
	p.printOperator(v)
	case *Bool:
	var s string
	if v.Value {
	s = "true"
	} else {
	s = "false"
	}
	p.printToken(s, v.LiteralPos)
	case *String:
	p.printToken(strconv.Quote(v.Value), v.LiteralPos)
	case *List:
	p.printList(v.Values, v.LBracePos, v.RBracePos)
	case *Map:
	p.printMap(v)
	default:
	panic(fmt.Errorf("bad property type: %s", value.Type()))
	}
	}

	func (p *printer) printList(list []Expression, pos, endPos scanner.Position) {
	p.requestSpace()
	p.printToken("[", pos)
	if len(list) > 1 \|\| pos.Line != endPos.Line {
	p.requestNewline()
	p.indent(p.curIndent() + 4)
	for _, value := range list {
	p.printExpression(value)
	p.printToken(",", noPos)
	p.requestNewline()
	}
	p.unindent(endPos)
	} else {
	for _, value := range list {
	p.printExpression(value)
	}
	}
	p.printToken("]", endPos)
	}

	func (p printer) printMap(m Map) {
	p.requestSpace()
	p.printToken("{", m.LBracePos)
	if len(m.Properties) > 0 \|\| m.LBracePos.Line != m.RBracePos.Line {
	p.requestNewline()
	p.indent(p.curIndent() + 4)
	for _, prop := range m.Properties {
	p.printProperty(prop)
	p.printToken(",", noPos)
	p.requestNewline()
	}
	p.unindent(m.RBracePos)
	}
	p.printToken("}", m.RBracePos)
	}

	func (p printer) printOperator(operator Operator) {
	p.printExpression(operator.Args[0])
	p.requestSpace()
	p.printToken(string(operator.Operator), operator.OperatorPos)
	if operator.Args[0].End().Line == operator.Args[1].Pos().Line {
	p.requestSpace()
	} else {
	p.requestNewline()
	}
	p.printExpression(operator.Args[1])
	}

	func (p printer) printProperty(property Property) {
	p.printToken(property.Name, property.NamePos)
	p.printToken(":", property.ColonPos)
	p.requestSpace()
	p.printExpression(property.Value)
	}

	// Print a single token, including any necessary comments or whitespace between
	// this token and the previously printed token
	func (p *printer) printToken(s string, pos scanner.Position) {
	newline := p.pendingNewline != 0

	if pos == noPos {
	pos = p.pos
	}

	if newline {
	p.printEndOfLineCommentsBefore(pos)
	p.requestNewlinesForPos(pos)
	}

	p.printInLineCommentsBefore(pos)

	p.flushSpace()

	p.output = append(p.output, s...)

	p.pos = pos
	}

	// Print any in-line (single line /* */) comments that appear _before_ pos
	func (p *printer) printInLineCommentsBefore(pos scanner.Position) {
	for p.curComment < len(p.comments) && p.comments[p.curComment].Pos().Offset < pos.Offset {
	c := p.comments[p.curComment]
	if c.Comments[0].Comment[0][0:2] == "//" \|\| len(c.Comments[0].Comment) > 1 {
	p.skippedComments = append(p.skippedComments, c)
	} else {
	p.printComment(c)
	p.requestSpace()
	}
	p.curComment++
	}
	}

	// Print any comments, including end of line comments, that appear _before_ the line specified
	// by pos
	func (p *printer) printEndOfLineCommentsBefore(pos scanner.Position) {
	if len(p.skippedComments) > 0 {
	for _, c := range p.skippedComments {
	p.printComment(c)
	}
	p._requestNewline()
	p.skippedComments = nil
	}
	for p.curComment < len(p.comments) && p.comments[p.curComment].Pos().Line < pos.Line {
	c := p.comments[p.curComment]
	p.printComment(c)
	p._requestNewline()
	p.curComment++
	}
	}

	// Compare the line numbers of the previous and current positions to determine whether extra
	// newlines should be inserted. A second newline is allowed anywhere requestNewline() is called.
	func (p *printer) requestNewlinesForPos(pos scanner.Position) bool {
	if pos.Line > p.pos.Line {
	p._requestNewline()
	if pos.Line > p.pos.Line+1 {
	p.pendingNewline = 2
	}
	return true
	}

	return false
	}

	func (p *printer) requestSpace() {
	p.pendingSpace = true
	}

	// Ask for a newline to be inserted before the next token, but do not insert any comments. Used
	// by the comment printers.
	func (p *printer) _requestNewline() {
	if p.pendingNewline == 0 {
	p.pendingNewline = 1
	}
	}

	// Ask for a newline to be inserted before the next token. Also inserts any end-of line comments
	// for the current line
	func (p *printer) requestNewline() {
	pos := p.pos
	pos.Line++
	p.printEndOfLineCommentsBefore(pos)
	p._requestNewline()
	}

	// Ask for two newlines to be inserted before the next token. Also inserts any end-of line comments
	// for the current line
	func (p *printer) requestDoubleNewline() {
	p.requestNewline()
	p.pendingNewline = 2
	}

	// Flush any pending whitespace, ignoring pending spaces if there is a pending newline
	func (p *printer) flushSpace() {
	if p.pendingNewline == 1 {
	p.output = append(p.output, '\n')
	p.pad(p.curIndent())
	} else if p.pendingNewline == 2 {
	p.output = append(p.output, "\n\n"...)
	p.pad(p.curIndent())
	} else if p.pendingSpace == true && p.pendingNewline != -1 {
	p.output = append(p.output, ' ')
	}

	p.pendingSpace = false
	p.pendingNewline = 0
	}

	// Print a single comment, which may be a multi-line comment
	func (p printer) printComment(cg CommentGroup) {
	for _, comment := range cg.Comments {
	if !p.requestNewlinesForPos(comment.Pos()) {
	p.requestSpace()
	}
	for i, line := range comment.Comment {
	line = strings.TrimRightFunc(line, unicode.IsSpace)
	p.flushSpace()
	if i != 0 {
	lineIndent := strings.IndexFunc(line, func(r rune) bool { return !unicode.IsSpace(r) })
	lineIndent = max(lineIndent, p.curIndent())
	p.pad(lineIndent - p.curIndent())
	}
	p.output = append(p.output, strings.TrimSpace(line)...)
	if i < len(comment.Comment)-1 {
	p._requestNewline()
	}
	}
	p.pos = comment.End()
	}
	}

	// Print any comments that occur after the last token, and a trailing newline
	func (p *printer) flush() {
	for _, c := range p.skippedComments {
	if !p.requestNewlinesForPos(c.Pos()) {
	p.requestSpace()
	}
	p.printComment(c)
	}
	for p.curComment < len(p.comments) {
	p.printComment(p.comments[p.curComment])
	p.curComment++
	}
	p.output = append(p.output, '\n')
	}

	// Print whitespace to pad from column l to column max
	func (p *printer) pad(l int) {
	if l > len(p.wsBuf) {
	p.wsBuf = make([]byte, l)
	for i := range p.wsBuf {
	p.wsBuf[i] = ' '
	}
	}
	p.output = append(p.output, p.wsBuf[0:l]...)
	}

	func (p *printer) indent(i int) {
	p.indentList = append(p.indentList, i)
	}

	func (p *printer) unindent(pos scanner.Position) {
	p.printEndOfLineCommentsBefore(pos)
	p.indentList = p.indentList[0 : len(p.indentList)-1]
	}

	func (p *printer) curIndent() int {
	return p.indentList[len(p.indentList)-1]
	}

	func max(a, b int) int {
	if a > b {
	return a
	} else {
	return b
	}
	}