847 lines
18 KiB
Go
847 lines
18 KiB
Go
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// Package parser provides a handlebars syntax analyser. It consumes the tokens provided by the lexer to build an AST.
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package parser
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import (
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"fmt"
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"regexp"
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"runtime"
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"strconv"
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"github.com/aymerick/raymond/ast"
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"github.com/aymerick/raymond/lexer"
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)
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// References:
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// - https://github.com/wycats/handlebars.js/blob/master/src/handlebars.yy
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// - https://github.com/golang/go/blob/master/src/text/template/parse/parse.go
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// parser is a syntax analyzer.
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type parser struct {
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// Lexer
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lex *lexer.Lexer
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// Root node
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root ast.Node
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// Tokens parsed but not consumed yet
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tokens []*lexer.Token
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// All tokens have been retreieved from lexer
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lexOver bool
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}
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var (
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rOpenComment = regexp.MustCompile(`^\{\{~?!-?-?`)
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rCloseComment = regexp.MustCompile(`-?-?~?\}\}$`)
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rOpenAmp = regexp.MustCompile(`^\{\{~?&`)
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)
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// new instanciates a new parser
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func new(input string) *parser {
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return &parser{
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lex: lexer.Scan(input),
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}
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}
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// Parse analyzes given input and returns the AST root node.
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func Parse(input string) (result *ast.Program, err error) {
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// recover error
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defer errRecover(&err)
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parser := new(input)
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// parse
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result = parser.parseProgram()
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// check last token
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token := parser.shift()
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if token.Kind != lexer.TokenEOF {
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// Parsing ended before EOF
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errToken(token, "Syntax error")
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}
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// fix whitespaces
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processWhitespaces(result)
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// named returned values
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return
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}
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// errRecover recovers parsing panic
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func errRecover(errp *error) {
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e := recover()
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if e != nil {
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switch err := e.(type) {
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case runtime.Error:
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panic(e)
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case error:
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*errp = err
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default:
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panic(e)
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}
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}
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}
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// errPanic panics
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func errPanic(err error, line int) {
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panic(fmt.Errorf("Parse error on line %d:\n%s", line, err))
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}
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// errNode panics with given node infos
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func errNode(node ast.Node, msg string) {
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errPanic(fmt.Errorf("%s\nNode: %s", msg, node), node.Location().Line)
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}
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// errNode panics with given Token infos
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func errToken(tok *lexer.Token, msg string) {
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errPanic(fmt.Errorf("%s\nToken: %s", msg, tok), tok.Line)
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}
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// errNode panics because of an unexpected Token kind
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func errExpected(expect lexer.TokenKind, tok *lexer.Token) {
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errPanic(fmt.Errorf("Expecting %s, got: '%s'", expect, tok), tok.Line)
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}
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// program : statement*
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func (p *parser) parseProgram() *ast.Program {
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result := ast.NewProgram(p.next().Pos, p.next().Line)
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for p.isStatement() {
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result.AddStatement(p.parseStatement())
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}
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return result
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}
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// statement : mustache | block | rawBlock | partial | content | COMMENT
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func (p *parser) parseStatement() ast.Node {
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var result ast.Node
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tok := p.next()
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switch tok.Kind {
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case lexer.TokenOpen, lexer.TokenOpenUnescaped:
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// mustache
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result = p.parseMustache()
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case lexer.TokenOpenBlock:
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// block
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result = p.parseBlock()
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case lexer.TokenOpenInverse:
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// block
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result = p.parseInverse()
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case lexer.TokenOpenRawBlock:
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// rawBlock
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result = p.parseRawBlock()
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case lexer.TokenOpenPartial:
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// partial
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result = p.parsePartial()
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case lexer.TokenContent:
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// content
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result = p.parseContent()
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case lexer.TokenComment:
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// COMMENT
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result = p.parseComment()
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}
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return result
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}
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// isStatement returns true if next token starts a statement
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func (p *parser) isStatement() bool {
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if !p.have(1) {
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return false
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}
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switch p.next().Kind {
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case lexer.TokenOpen, lexer.TokenOpenUnescaped, lexer.TokenOpenBlock,
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lexer.TokenOpenInverse, lexer.TokenOpenRawBlock, lexer.TokenOpenPartial,
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lexer.TokenContent, lexer.TokenComment:
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return true
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}
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return false
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}
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// content : CONTENT
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func (p *parser) parseContent() *ast.ContentStatement {
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// CONTENT
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tok := p.shift()
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if tok.Kind != lexer.TokenContent {
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// @todo This check can be removed if content is optional in a raw block
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errExpected(lexer.TokenContent, tok)
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}
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return ast.NewContentStatement(tok.Pos, tok.Line, tok.Val)
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}
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// COMMENT
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func (p *parser) parseComment() *ast.CommentStatement {
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// COMMENT
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tok := p.shift()
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value := rOpenComment.ReplaceAllString(tok.Val, "")
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value = rCloseComment.ReplaceAllString(value, "")
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result := ast.NewCommentStatement(tok.Pos, tok.Line, value)
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result.Strip = ast.NewStripForStr(tok.Val)
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return result
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}
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// param* hash?
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func (p *parser) parseExpressionParamsHash() ([]ast.Node, *ast.Hash) {
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var params []ast.Node
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var hash *ast.Hash
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// params*
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if p.isParam() {
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params = p.parseParams()
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}
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// hash?
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if p.isHashSegment() {
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hash = p.parseHash()
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}
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return params, hash
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}
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// helperName param* hash?
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func (p *parser) parseExpression(tok *lexer.Token) *ast.Expression {
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result := ast.NewExpression(tok.Pos, tok.Line)
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// helperName
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result.Path = p.parseHelperName()
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// param* hash?
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result.Params, result.Hash = p.parseExpressionParamsHash()
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return result
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}
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// rawBlock : openRawBlock content endRawBlock
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// openRawBlock : OPEN_RAW_BLOCK helperName param* hash? CLOSE_RAW_BLOCK
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// endRawBlock : OPEN_END_RAW_BLOCK helperName CLOSE_RAW_BLOCK
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func (p *parser) parseRawBlock() *ast.BlockStatement {
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// OPEN_RAW_BLOCK
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tok := p.shift()
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result := ast.NewBlockStatement(tok.Pos, tok.Line)
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// helperName param* hash?
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result.Expression = p.parseExpression(tok)
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openName := result.Expression.Canonical()
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// CLOSE_RAW_BLOCK
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tok = p.shift()
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if tok.Kind != lexer.TokenCloseRawBlock {
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errExpected(lexer.TokenCloseRawBlock, tok)
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}
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// content
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// @todo Is content mandatory in a raw block ?
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content := p.parseContent()
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program := ast.NewProgram(tok.Pos, tok.Line)
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program.AddStatement(content)
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result.Program = program
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// OPEN_END_RAW_BLOCK
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tok = p.shift()
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if tok.Kind != lexer.TokenOpenEndRawBlock {
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// should never happen as it is caught by lexer
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errExpected(lexer.TokenOpenEndRawBlock, tok)
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}
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// helperName
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endID := p.parseHelperName()
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closeName, ok := ast.HelperNameStr(endID)
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if !ok {
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errNode(endID, "Erroneous closing expression")
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}
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if openName != closeName {
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errNode(endID, fmt.Sprintf("%s doesn't match %s", openName, closeName))
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}
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// CLOSE_RAW_BLOCK
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tok = p.shift()
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if tok.Kind != lexer.TokenCloseRawBlock {
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errExpected(lexer.TokenCloseRawBlock, tok)
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}
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return result
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}
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// block : openBlock program inverseChain? closeBlock
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func (p *parser) parseBlock() *ast.BlockStatement {
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// openBlock
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result, blockParams := p.parseOpenBlock()
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// program
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program := p.parseProgram()
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program.BlockParams = blockParams
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result.Program = program
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// inverseChain?
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if p.isInverseChain() {
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result.Inverse = p.parseInverseChain()
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}
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// closeBlock
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p.parseCloseBlock(result)
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setBlockInverseStrip(result)
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return result
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}
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// setBlockInverseStrip is called when parsing `block` (openBlock | openInverse) and `inverseChain`
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//
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// TODO: This was totally cargo culted ! CHECK THAT !
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//
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// cf. prepareBlock() in:
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// https://github.com/wycats/handlebars.js/blob/master/lib/handlebars/compiler/helper.js
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func setBlockInverseStrip(block *ast.BlockStatement) {
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if block.Inverse == nil {
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return
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}
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if block.Inverse.Chained {
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b, _ := block.Inverse.Body[0].(*ast.BlockStatement)
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b.CloseStrip = block.CloseStrip
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}
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block.InverseStrip = block.Inverse.Strip
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}
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// block : openInverse program inverseAndProgram? closeBlock
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func (p *parser) parseInverse() *ast.BlockStatement {
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// openInverse
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result, blockParams := p.parseOpenBlock()
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// program
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program := p.parseProgram()
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program.BlockParams = blockParams
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result.Inverse = program
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// inverseAndProgram?
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if p.isInverse() {
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result.Program = p.parseInverseAndProgram()
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}
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// closeBlock
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p.parseCloseBlock(result)
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setBlockInverseStrip(result)
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return result
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}
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// helperName param* hash? blockParams?
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func (p *parser) parseOpenBlockExpression(tok *lexer.Token) (*ast.BlockStatement, []string) {
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var blockParams []string
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result := ast.NewBlockStatement(tok.Pos, tok.Line)
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// helperName param* hash?
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result.Expression = p.parseExpression(tok)
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// blockParams?
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if p.isBlockParams() {
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blockParams = p.parseBlockParams()
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}
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// named returned values
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return result, blockParams
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}
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// inverseChain : openInverseChain program inverseChain?
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// | inverseAndProgram
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func (p *parser) parseInverseChain() *ast.Program {
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if p.isInverse() {
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// inverseAndProgram
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return p.parseInverseAndProgram()
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}
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result := ast.NewProgram(p.next().Pos, p.next().Line)
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// openInverseChain
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block, blockParams := p.parseOpenBlock()
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// program
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program := p.parseProgram()
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program.BlockParams = blockParams
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block.Program = program
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// inverseChain?
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if p.isInverseChain() {
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block.Inverse = p.parseInverseChain()
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}
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setBlockInverseStrip(block)
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result.Chained = true
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result.AddStatement(block)
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return result
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}
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// Returns true if current token starts an inverse chain
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func (p *parser) isInverseChain() bool {
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return p.isOpenInverseChain() || p.isInverse()
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}
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// inverseAndProgram : INVERSE program
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func (p *parser) parseInverseAndProgram() *ast.Program {
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// INVERSE
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tok := p.shift()
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// program
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result := p.parseProgram()
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result.Strip = ast.NewStripForStr(tok.Val)
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return result
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}
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// openBlock : OPEN_BLOCK helperName param* hash? blockParams? CLOSE
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// openInverse : OPEN_INVERSE helperName param* hash? blockParams? CLOSE
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// openInverseChain: OPEN_INVERSE_CHAIN helperName param* hash? blockParams? CLOSE
|
||
|
|
func (p *parser) parseOpenBlock() (*ast.BlockStatement, []string) {
|
||
|
|
// OPEN_BLOCK | OPEN_INVERSE | OPEN_INVERSE_CHAIN
|
||
|
|
tok := p.shift()
|
||
|
|
|
||
|
|
// helperName param* hash? blockParams?
|
||
|
|
result, blockParams := p.parseOpenBlockExpression(tok)
|
||
|
|
|
||
|
|
// CLOSE
|
||
|
|
tokClose := p.shift()
|
||
|
|
if tokClose.Kind != lexer.TokenClose {
|
||
|
|
errExpected(lexer.TokenClose, tokClose)
|
||
|
|
}
|
||
|
|
|
||
|
|
result.OpenStrip = ast.NewStrip(tok.Val, tokClose.Val)
|
||
|
|
|
||
|
|
// named returned values
|
||
|
|
return result, blockParams
|
||
|
|
}
|
||
|
|
|
||
|
|
// closeBlock : OPEN_ENDBLOCK helperName CLOSE
|
||
|
|
func (p *parser) parseCloseBlock(block *ast.BlockStatement) {
|
||
|
|
// OPEN_ENDBLOCK
|
||
|
|
tok := p.shift()
|
||
|
|
if tok.Kind != lexer.TokenOpenEndBlock {
|
||
|
|
errExpected(lexer.TokenOpenEndBlock, tok)
|
||
|
|
}
|
||
|
|
|
||
|
|
// helperName
|
||
|
|
endID := p.parseHelperName()
|
||
|
|
|
||
|
|
closeName, ok := ast.HelperNameStr(endID)
|
||
|
|
if !ok {
|
||
|
|
errNode(endID, "Erroneous closing expression")
|
||
|
|
}
|
||
|
|
|
||
|
|
openName := block.Expression.Canonical()
|
||
|
|
if openName != closeName {
|
||
|
|
errNode(endID, fmt.Sprintf("%s doesn't match %s", openName, closeName))
|
||
|
|
}
|
||
|
|
|
||
|
|
// CLOSE
|
||
|
|
tokClose := p.shift()
|
||
|
|
if tokClose.Kind != lexer.TokenClose {
|
||
|
|
errExpected(lexer.TokenClose, tokClose)
|
||
|
|
}
|
||
|
|
|
||
|
|
block.CloseStrip = ast.NewStrip(tok.Val, tokClose.Val)
|
||
|
|
}
|
||
|
|
|
||
|
|
// mustache : OPEN helperName param* hash? CLOSE
|
||
|
|
// | OPEN_UNESCAPED helperName param* hash? CLOSE_UNESCAPED
|
||
|
|
func (p *parser) parseMustache() *ast.MustacheStatement {
|
||
|
|
// OPEN | OPEN_UNESCAPED
|
||
|
|
tok := p.shift()
|
||
|
|
|
||
|
|
closeToken := lexer.TokenClose
|
||
|
|
if tok.Kind == lexer.TokenOpenUnescaped {
|
||
|
|
closeToken = lexer.TokenCloseUnescaped
|
||
|
|
}
|
||
|
|
|
||
|
|
unescaped := false
|
||
|
|
if (tok.Kind == lexer.TokenOpenUnescaped) || (rOpenAmp.MatchString(tok.Val)) {
|
||
|
|
unescaped = true
|
||
|
|
}
|
||
|
|
|
||
|
|
result := ast.NewMustacheStatement(tok.Pos, tok.Line, unescaped)
|
||
|
|
|
||
|
|
// helperName param* hash?
|
||
|
|
result.Expression = p.parseExpression(tok)
|
||
|
|
|
||
|
|
// CLOSE | CLOSE_UNESCAPED
|
||
|
|
tokClose := p.shift()
|
||
|
|
if tokClose.Kind != closeToken {
|
||
|
|
errExpected(closeToken, tokClose)
|
||
|
|
}
|
||
|
|
|
||
|
|
result.Strip = ast.NewStrip(tok.Val, tokClose.Val)
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// partial : OPEN_PARTIAL partialName param* hash? CLOSE
|
||
|
|
func (p *parser) parsePartial() *ast.PartialStatement {
|
||
|
|
// OPEN_PARTIAL
|
||
|
|
tok := p.shift()
|
||
|
|
|
||
|
|
result := ast.NewPartialStatement(tok.Pos, tok.Line)
|
||
|
|
|
||
|
|
// partialName
|
||
|
|
result.Name = p.parsePartialName()
|
||
|
|
|
||
|
|
// param* hash?
|
||
|
|
result.Params, result.Hash = p.parseExpressionParamsHash()
|
||
|
|
|
||
|
|
// CLOSE
|
||
|
|
tokClose := p.shift()
|
||
|
|
if tokClose.Kind != lexer.TokenClose {
|
||
|
|
errExpected(lexer.TokenClose, tokClose)
|
||
|
|
}
|
||
|
|
|
||
|
|
result.Strip = ast.NewStrip(tok.Val, tokClose.Val)
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// helperName | sexpr
|
||
|
|
func (p *parser) parseHelperNameOrSexpr() ast.Node {
|
||
|
|
if p.isSexpr() {
|
||
|
|
// sexpr
|
||
|
|
return p.parseSexpr()
|
||
|
|
}
|
||
|
|
|
||
|
|
// helperName
|
||
|
|
return p.parseHelperName()
|
||
|
|
}
|
||
|
|
|
||
|
|
// param : helperName | sexpr
|
||
|
|
func (p *parser) parseParam() ast.Node {
|
||
|
|
return p.parseHelperNameOrSexpr()
|
||
|
|
}
|
||
|
|
|
||
|
|
// Returns true if next tokens represent a `param`
|
||
|
|
func (p *parser) isParam() bool {
|
||
|
|
return (p.isSexpr() || p.isHelperName()) && !p.isHashSegment()
|
||
|
|
}
|
||
|
|
|
||
|
|
// param*
|
||
|
|
func (p *parser) parseParams() []ast.Node {
|
||
|
|
var result []ast.Node
|
||
|
|
|
||
|
|
for p.isParam() {
|
||
|
|
result = append(result, p.parseParam())
|
||
|
|
}
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// sexpr : OPEN_SEXPR helperName param* hash? CLOSE_SEXPR
|
||
|
|
func (p *parser) parseSexpr() *ast.SubExpression {
|
||
|
|
// OPEN_SEXPR
|
||
|
|
tok := p.shift()
|
||
|
|
|
||
|
|
result := ast.NewSubExpression(tok.Pos, tok.Line)
|
||
|
|
|
||
|
|
// helperName param* hash?
|
||
|
|
result.Expression = p.parseExpression(tok)
|
||
|
|
|
||
|
|
// CLOSE_SEXPR
|
||
|
|
tok = p.shift()
|
||
|
|
if tok.Kind != lexer.TokenCloseSexpr {
|
||
|
|
errExpected(lexer.TokenCloseSexpr, tok)
|
||
|
|
}
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// hash : hashSegment+
|
||
|
|
func (p *parser) parseHash() *ast.Hash {
|
||
|
|
var pairs []*ast.HashPair
|
||
|
|
|
||
|
|
for p.isHashSegment() {
|
||
|
|
pairs = append(pairs, p.parseHashSegment())
|
||
|
|
}
|
||
|
|
|
||
|
|
firstLoc := pairs[0].Location()
|
||
|
|
|
||
|
|
result := ast.NewHash(firstLoc.Pos, firstLoc.Line)
|
||
|
|
result.Pairs = pairs
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// returns true if next tokens represents a `hashSegment`
|
||
|
|
func (p *parser) isHashSegment() bool {
|
||
|
|
return p.have(2) && (p.next().Kind == lexer.TokenID) && (p.nextAt(1).Kind == lexer.TokenEquals)
|
||
|
|
}
|
||
|
|
|
||
|
|
// hashSegment : ID EQUALS param
|
||
|
|
func (p *parser) parseHashSegment() *ast.HashPair {
|
||
|
|
// ID
|
||
|
|
tok := p.shift()
|
||
|
|
|
||
|
|
// EQUALS
|
||
|
|
p.shift()
|
||
|
|
|
||
|
|
// param
|
||
|
|
param := p.parseParam()
|
||
|
|
|
||
|
|
result := ast.NewHashPair(tok.Pos, tok.Line)
|
||
|
|
result.Key = tok.Val
|
||
|
|
result.Val = param
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// blockParams : OPEN_BLOCK_PARAMS ID+ CLOSE_BLOCK_PARAMS
|
||
|
|
func (p *parser) parseBlockParams() []string {
|
||
|
|
var result []string
|
||
|
|
|
||
|
|
// OPEN_BLOCK_PARAMS
|
||
|
|
tok := p.shift()
|
||
|
|
|
||
|
|
// ID+
|
||
|
|
for p.isID() {
|
||
|
|
result = append(result, p.shift().Val)
|
||
|
|
}
|
||
|
|
|
||
|
|
if len(result) == 0 {
|
||
|
|
errExpected(lexer.TokenID, p.next())
|
||
|
|
}
|
||
|
|
|
||
|
|
// CLOSE_BLOCK_PARAMS
|
||
|
|
tok = p.shift()
|
||
|
|
if tok.Kind != lexer.TokenCloseBlockParams {
|
||
|
|
errExpected(lexer.TokenCloseBlockParams, tok)
|
||
|
|
}
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// helperName : path | dataName | STRING | NUMBER | BOOLEAN | UNDEFINED | NULL
|
||
|
|
func (p *parser) parseHelperName() ast.Node {
|
||
|
|
var result ast.Node
|
||
|
|
|
||
|
|
tok := p.next()
|
||
|
|
|
||
|
|
switch tok.Kind {
|
||
|
|
case lexer.TokenBoolean:
|
||
|
|
// BOOLEAN
|
||
|
|
p.shift()
|
||
|
|
result = ast.NewBooleanLiteral(tok.Pos, tok.Line, (tok.Val == "true"), tok.Val)
|
||
|
|
case lexer.TokenNumber:
|
||
|
|
// NUMBER
|
||
|
|
p.shift()
|
||
|
|
|
||
|
|
val, isInt := parseNumber(tok)
|
||
|
|
result = ast.NewNumberLiteral(tok.Pos, tok.Line, val, isInt, tok.Val)
|
||
|
|
case lexer.TokenString:
|
||
|
|
// STRING
|
||
|
|
p.shift()
|
||
|
|
result = ast.NewStringLiteral(tok.Pos, tok.Line, tok.Val)
|
||
|
|
case lexer.TokenData:
|
||
|
|
// dataName
|
||
|
|
result = p.parseDataName()
|
||
|
|
default:
|
||
|
|
// path
|
||
|
|
result = p.parsePath(false)
|
||
|
|
}
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// parseNumber parses a number
|
||
|
|
func parseNumber(tok *lexer.Token) (result float64, isInt bool) {
|
||
|
|
var valInt int
|
||
|
|
var err error
|
||
|
|
|
||
|
|
valInt, err = strconv.Atoi(tok.Val)
|
||
|
|
if err == nil {
|
||
|
|
isInt = true
|
||
|
|
|
||
|
|
result = float64(valInt)
|
||
|
|
} else {
|
||
|
|
isInt = false
|
||
|
|
|
||
|
|
result, err = strconv.ParseFloat(tok.Val, 64)
|
||
|
|
if err != nil {
|
||
|
|
errToken(tok, fmt.Sprintf("Failed to parse number: %s", tok.Val))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// named returned values
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
// Returns true if next tokens represent a `helperName`
|
||
|
|
func (p *parser) isHelperName() bool {
|
||
|
|
switch p.next().Kind {
|
||
|
|
case lexer.TokenBoolean, lexer.TokenNumber, lexer.TokenString, lexer.TokenData, lexer.TokenID:
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
|
||
|
|
// partialName : helperName | sexpr
|
||
|
|
func (p *parser) parsePartialName() ast.Node {
|
||
|
|
return p.parseHelperNameOrSexpr()
|
||
|
|
}
|
||
|
|
|
||
|
|
// dataName : DATA pathSegments
|
||
|
|
func (p *parser) parseDataName() *ast.PathExpression {
|
||
|
|
// DATA
|
||
|
|
p.shift()
|
||
|
|
|
||
|
|
// pathSegments
|
||
|
|
return p.parsePath(true)
|
||
|
|
}
|
||
|
|
|
||
|
|
// path : pathSegments
|
||
|
|
// pathSegments : pathSegments SEP ID
|
||
|
|
// | ID
|
||
|
|
func (p *parser) parsePath(data bool) *ast.PathExpression {
|
||
|
|
var tok *lexer.Token
|
||
|
|
|
||
|
|
// ID
|
||
|
|
tok = p.shift()
|
||
|
|
if tok.Kind != lexer.TokenID {
|
||
|
|
errExpected(lexer.TokenID, tok)
|
||
|
|
}
|
||
|
|
|
||
|
|
result := ast.NewPathExpression(tok.Pos, tok.Line, data)
|
||
|
|
result.Part(tok.Val)
|
||
|
|
|
||
|
|
for p.isPathSep() {
|
||
|
|
// SEP
|
||
|
|
tok = p.shift()
|
||
|
|
result.Sep(tok.Val)
|
||
|
|
|
||
|
|
// ID
|
||
|
|
tok = p.shift()
|
||
|
|
if tok.Kind != lexer.TokenID {
|
||
|
|
errExpected(lexer.TokenID, tok)
|
||
|
|
}
|
||
|
|
|
||
|
|
result.Part(tok.Val)
|
||
|
|
|
||
|
|
if len(result.Parts) > 0 {
|
||
|
|
switch tok.Val {
|
||
|
|
case "..", ".", "this":
|
||
|
|
errToken(tok, "Invalid path: "+result.Original)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// Ensures there is token to parse at given index
|
||
|
|
func (p *parser) ensure(index int) {
|
||
|
|
if p.lexOver {
|
||
|
|
// nothing more to grab
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
nb := index + 1
|
||
|
|
|
||
|
|
for len(p.tokens) < nb {
|
||
|
|
// fetch next token
|
||
|
|
tok := p.lex.NextToken()
|
||
|
|
|
||
|
|
// queue it
|
||
|
|
p.tokens = append(p.tokens, &tok)
|
||
|
|
|
||
|
|
if (tok.Kind == lexer.TokenEOF) || (tok.Kind == lexer.TokenError) {
|
||
|
|
p.lexOver = true
|
||
|
|
break
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// have returns true is there are a list given number of tokens to consume left
|
||
|
|
func (p *parser) have(nb int) bool {
|
||
|
|
p.ensure(nb - 1)
|
||
|
|
|
||
|
|
return len(p.tokens) >= nb
|
||
|
|
}
|
||
|
|
|
||
|
|
// nextAt returns next token at given index, without consuming it
|
||
|
|
func (p *parser) nextAt(index int) *lexer.Token {
|
||
|
|
p.ensure(index)
|
||
|
|
|
||
|
|
return p.tokens[index]
|
||
|
|
}
|
||
|
|
|
||
|
|
// next returns next token without consuming it
|
||
|
|
func (p *parser) next() *lexer.Token {
|
||
|
|
return p.nextAt(0)
|
||
|
|
}
|
||
|
|
|
||
|
|
// shift returns next token and remove it from the tokens buffer
|
||
|
|
//
|
||
|
|
// Panics if next token is `TokenError`
|
||
|
|
func (p *parser) shift() *lexer.Token {
|
||
|
|
var result *lexer.Token
|
||
|
|
|
||
|
|
p.ensure(0)
|
||
|
|
|
||
|
|
result, p.tokens = p.tokens[0], p.tokens[1:]
|
||
|
|
|
||
|
|
// check error token
|
||
|
|
if result.Kind == lexer.TokenError {
|
||
|
|
errToken(result, "Lexer error")
|
||
|
|
}
|
||
|
|
|
||
|
|
return result
|
||
|
|
}
|
||
|
|
|
||
|
|
// isToken returns true if next token is of given type
|
||
|
|
func (p *parser) isToken(kind lexer.TokenKind) bool {
|
||
|
|
return p.have(1) && p.next().Kind == kind
|
||
|
|
}
|
||
|
|
|
||
|
|
// isSexpr returns true if next token starts a sexpr
|
||
|
|
func (p *parser) isSexpr() bool {
|
||
|
|
return p.isToken(lexer.TokenOpenSexpr)
|
||
|
|
}
|
||
|
|
|
||
|
|
// isPathSep returns true if next token is a path separator
|
||
|
|
func (p *parser) isPathSep() bool {
|
||
|
|
return p.isToken(lexer.TokenSep)
|
||
|
|
}
|
||
|
|
|
||
|
|
// isID returns true if next token is an ID
|
||
|
|
func (p *parser) isID() bool {
|
||
|
|
return p.isToken(lexer.TokenID)
|
||
|
|
}
|
||
|
|
|
||
|
|
// isBlockParams returns true if next token starts a block params
|
||
|
|
func (p *parser) isBlockParams() bool {
|
||
|
|
return p.isToken(lexer.TokenOpenBlockParams)
|
||
|
|
}
|
||
|
|
|
||
|
|
// isInverse returns true if next token starts an INVERSE sequence
|
||
|
|
func (p *parser) isInverse() bool {
|
||
|
|
return p.isToken(lexer.TokenInverse)
|
||
|
|
}
|
||
|
|
|
||
|
|
// isOpenInverseChain returns true if next token is OPEN_INVERSE_CHAIN
|
||
|
|
func (p *parser) isOpenInverseChain() bool {
|
||
|
|
return p.isToken(lexer.TokenOpenInverseChain)
|
||
|
|
}
|