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state.go
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state.go
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/*
* Copyright 2016-2018 Dgraph Labs, Inc.
*
* This file is available under the Apache License, Version 2.0,
* with the Commons Clause restriction.
*/
package schema
import (
"github.com/dgraph-io/dgraph/lex"
)
// Constants representing type of different graphql lexed items.
const (
itemText lex.ItemType = 5 + iota // plain text
itemLeftCurl // left curly bracket
itemRightCurl // right curly bracket
itemColon // colon
itemLeftRound // left round bracket
itemRightRound // right round bracket
itemAt
itemComma
itemNewLine
itemDot
itemUnderscore
itemLeftSquare
itemRightSquare
)
func lexText(l *lex.Lexer) lex.StateFn {
Loop:
for {
switch r := l.Next(); {
case r == lex.EOF:
break Loop
case isNameBegin(r):
l.Backup()
return lexWord
case isSpace(r):
l.Ignore()
case isEndOfLine(r):
l.Emit(itemNewLine)
case r == '.':
l.Emit(itemDot)
case r == ',':
l.Emit(itemComma)
case r == '<':
if err := lex.LexIRIRef(l, itemText); err != nil {
return l.Errorf("Invalid schema: %v", err)
}
case r == '{':
l.Emit(itemLeftCurl)
case r == '}':
l.Emit(itemRightCurl)
case r == '(':
l.Emit(itemLeftRound)
case r == ')':
l.Emit(itemRightRound)
case r == ':':
l.Emit(itemColon)
case r == '@':
l.Emit(itemAt)
case r == '[':
l.Emit(itemLeftSquare)
case r == ']':
l.Emit(itemRightSquare)
case r == '_':
// Predicates can start with _.
return lexWord
default:
return l.Errorf("Invalid schema. Unexpected %s", l.Input[l.Start:l.Pos])
}
}
if l.Pos > l.Start {
l.Emit(itemText)
}
l.Emit(lex.ItemEOF)
return nil
}
func lexWord(l *lex.Lexer) lex.StateFn {
for {
// The caller already checked isNameBegin, and absorbed one rune.
r := l.Next()
if isNameSuffix(r) {
continue
}
l.Backup()
l.Emit(itemText)
break
}
return lexText
}
// isNameBegin returns true if the rune is an alphabet.
func isNameBegin(r rune) bool {
switch {
case r >= 'a' && r <= 'z':
return true
case r >= 'A' && r <= 'Z':
return true
default:
return false
}
}
func isNameSuffix(r rune) bool {
if isNameBegin(r) {
return true
}
if r >= '0' && r <= '9' {
return true
}
if r == '_' || r == '.' || r == '-' { // Use by freebase.
return true
}
return false
}
// isSpace returns true if the rune is a tab or space.
func isSpace(r rune) bool {
return r == '\u0009' || r == '\u0020'
}
// isEndOfLine returns true if the rune is a Linefeed or a Carriage return.
func isEndOfLine(r rune) bool {
return r == '\n' || r == '\u000D'
}