Golang Lexer.AcceptRun方法代碼示例

// lexInside lexes the content inside a query block.
func lexInside(l *lex.Lexer) lex.StateFn {
	for {
		switch r := l.Next(); {
		case r == period:
			if l.Next() == period && l.Next() == period {
				return lexFragmentSpread
			}
			// We do not expect a period at all. If you do, you may want to
			// backup the two extra periods we try to read.
			return l.Errorf("Unrecognized character in lexInside: %#U", r)
		case r == rightCurl:
			l.Depth--
			l.Emit(itemRightCurl)
			if l.Depth == 0 {
				return lexText
			}
		case r == leftCurl:
			l.Depth++
			l.Emit(itemLeftCurl)
		case r == lex.EOF:
			return l.Errorf("Unclosed action")
		case isSpace(r) || isEndOfLine(r) || r == comma:
			l.Ignore()
		case isNameBegin(r):
			return lexName
		case r == '#':
			l.Backup()
			return lexComment
		case r == leftRound:
			l.Emit(itemLeftRound)
			l.AcceptRun(isSpace)
			l.Ignore()
			k := l.Next()
			if k == '_' || l.Depth != 1 || l.Mode == fragmentMode {
				l.Backup()
				l.Emit(itemArgument)
				return lexArgInside
			}
			// This is a generator function.
			l.Backup()
			l.Emit(itemGenerator)
			l.FilterDepth++
			return lexFilterInside
		case r == ':':
			return lexAlias
		case r == '@':
			return lexDirective
		default:
			return l.Errorf("Unrecognized character in lexInside: %#U", r)
		}
	}
}

func lexAlias(l *lex.Lexer) lex.StateFn {
	l.AcceptRun(isSpace)
	l.Ignore() // Any spaces encountered.
	for {
		r := l.Next()
		if isNameSuffix(r) {
			continue
		}
		l.Backup()
		l.Emit(itemAlias)
		break
	}
	return lexInside
}

func lexLanguage(l *lex.Lexer) lex.StateFn {
	r := l.Next()
	if r != '@' {
		return l.Errorf("Expected @ prefix for lexLanguage")
	}
	l.Ignore()
	r = l.Next()
	if !isLangTagPrefix(r) {
		return l.Errorf("Invalid language tag prefix: %v", r)
	}
	l.AcceptRun(isLangTag)
	l.Emit(itemLanguage)
	return lexText
}

// lexArgVal lexes and emits the value part of an argument.
func lexArgVal(l *lex.Lexer) lex.StateFn {
	l.AcceptRun(isSpace)
	l.Ignore() // Any spaces encountered.
	for {
		r := l.Next()
		if isSpace(r) || isEndOfLine(r) || r == rightRound || r == comma {
			l.Backup()
			l.Emit(itemArgVal)
			return lexArgInside
		}
		if r == lex.EOF {
			return l.Errorf("Reached lex.EOF while reading var value: %v",
				l.Input[l.Start:l.Pos])
		}
	}
}

func lexArgVal(l *lex.Lexer) lex.StateFn {
	l.AcceptRun(isSpace)
	l.Ignore() // Any spaces encountered.
	for {
		r := l.Next()
		if isSpace(r) || isEndOfLine(r) || r == ')' || r == ',' {
			l.Backup()
			l.Emit(itemArgVal)
			return lexArgInside
		}
		if r == lex.EOF {
			return l.Errorf("Reached lex.EOF while reading var value: %v",
				l.Input[l.Start:l.Pos])
		}
	}
	glog.Fatal("This shouldn't be reached.")
	return nil
}

// lexFilterFuncInside expects input to look like ("...", "...").
func lexFilterFuncInside(l *lex.Lexer) lex.StateFn {
	l.AcceptRun(isSpace)
	l.Ignore() // Any spaces encountered.

	for {
		r := l.Next()
		if isSpace(r) || r == ',' {
			l.Ignore()
		} else if r == leftRound {
			l.Emit(itemLeftRound)
		} else if r == rightRound {
			l.Emit(itemRightRound)
			return lexFilterInside
		} else if isEndLiteral(r) {
			l.Ignore()
			l.AcceptUntil(isEndLiteral) // This call will backup the ending ".
			l.Emit(itemFilterFuncArg)
			l.Next() // Consume " and ignore it.
			l.Ignore()
		} else {
			return l.Errorf("Expected quotation mark in lexFilterFuncArgs")
		}
	}
}