package qcode import ( "bytes" "errors" "fmt" "unicode" "unicode/utf8" ) var ( queryToken = []byte("query") mutationToken = []byte("mutation") subscriptionToken = []byte("subscription") trueToken = []byte("true") falseToken = []byte("false") quotesToken = []byte(`'"`) signsToken = []byte(`+-`) punctuatorToken = []byte(`!():=[]{|}`) spreadToken = []byte(`...`) digitToken = []byte(`0123456789`) dotToken = []byte(`.`) ) // Pos represents a byte position in the original input text from which // this template was parsed. type Pos int // item represents a token or text string returned from the scanner. type item struct { typ itemType // The type of this item. pos Pos // The starting position, in bytes, of this item in the input string. end Pos // The ending position, in bytes, of this item in the input string. line uint16 // The line number at the start of this item. } // itemType identifies the type of lex items. type itemType int const ( itemError itemType = iota // error occurred; value is text of error itemEOF itemName itemQuery itemMutation itemSub itemPunctuator itemArgsOpen itemArgsClose itemListOpen itemListClose itemObjOpen itemObjClose itemColon itemEquals itemDirective itemVariable itemSpread itemIntVal itemFloatVal itemStringVal itemBoolVal ) // !$():=@[]{|} var punctuators = map[rune]itemType{ '{': itemObjOpen, '}': itemObjClose, '[': itemListOpen, ']': itemListClose, '(': itemArgsOpen, ')': itemArgsClose, ':': itemColon, '=': itemEquals, } const eof = -1 // stateFn represents the state of the scanner as a function that returns the next state. type stateFn func(*lexer) stateFn // lexer holds the state of the scanner. type lexer struct { input []byte // the string being scanned pos Pos // current position in the input start Pos // start position of this item width Pos // width of last rune read from input items []item // array of scanned items itemsA [50]item line uint16 // 1+number of newlines seen err error } var zeroLex = lexer{} func (l *lexer) Reset() { *l = zeroLex } // next returns the next byte in the input. func (l *lexer) next() rune { if int(l.pos) >= len(l.input) { l.width = 0 return eof } r, w := utf8.DecodeRune(l.input[l.pos:]) l.width = Pos(w) l.pos += l.width if r == '\n' { l.line++ } return r } // peek returns but does not consume the next rune in the input. func (l *lexer) peek() rune { r := l.next() l.backup() return r } // backup steps back one rune. Can only be called once per call of next. func (l *lexer) backup() { l.pos -= l.width // Correct newline count. if l.width == 1 && l.input[l.pos] == '\n' { l.line-- } } func (l *lexer) current() (Pos, Pos) { return l.start, l.pos } // emit passes an item back to the client. func (l *lexer) emit(t itemType) { l.items = append(l.items, item{t, l.start, l.pos, l.line}) // Some items contain text internally. If so, count their newlines. switch t { case itemName: for i := l.start; i < l.pos; i++ { if l.input[i] == '\n' { l.line++ } } } l.start = l.pos } // ignore skips over the pending input before this point. func (l *lexer) ignore() { for i := l.start; i < l.pos; i++ { if l.input[i] == '\n' { l.line++ } } l.start = l.pos } // accept consumes the next rune if it's from the valid set. func (l *lexer) accept(valid []byte) bool { if bytes.ContainsRune(valid, l.next()) { return true } l.backup() return false } // acceptAlphaNum consumes a run of runes while they are alpha nums func (l *lexer) acceptAlphaNum() bool { n := 0 for r := l.next(); isAlphaNumeric(r); r = l.next() { n++ } l.backup() return (n != 0) } // acceptComment consumes a run of runes while till the end of line func (l *lexer) acceptComment() { n := 0 for r := l.next(); !isEndOfLine(r); r = l.next() { n++ } } // acceptRun consumes a run of runes from the valid set. func (l *lexer) acceptRun(valid []byte) { for bytes.ContainsRune(valid, l.next()) { } l.backup() } // errorf returns an error token and terminates the scan by passing // back a nil pointer that will be the next state, terminating l.nextItem. func (l *lexer) errorf(format string, args ...interface{}) stateFn { l.err = fmt.Errorf(format, args...) l.items = append(l.items, item{itemError, l.start, l.pos, l.line}) return nil } // lex creates a new scanner for the input string. func lex(l *lexer, input []byte) error { if len(input) == 0 { return errors.New("empty query") } l.input = input l.items = l.itemsA[:0] l.line = 1 l.run() if last := l.items[len(l.items)-1]; last.typ == itemError { return l.err } return nil } // run runs the state machine for the lexer. func (l *lexer) run() { for state := lexRoot; state != nil; { state = state(l) } } // lexInsideAction scans the elements inside action delimiters. func lexRoot(l *lexer) stateFn { r := l.next() switch { case r == eof: l.emit(itemEOF) return nil case isEndOfLine(r): l.ignore() case isSpace(r): l.ignore() case r == '#': l.ignore() l.acceptComment() l.ignore() case r == '@': l.ignore() if l.acceptAlphaNum() { l.emit(itemDirective) } case r == '$': l.ignore() if l.acceptAlphaNum() { s, e := l.current() lowercase(l.input, s, e) l.emit(itemVariable) } case contains(l.input, l.start, l.pos, punctuatorToken): if item, ok := punctuators[r]; ok { l.emit(item) } else { l.emit(itemPunctuator) } case r == '"' || r == '\'': l.backup() return lexString case r == '.': if len(l.input) >= 3 { if equals(l.input, 0, 3, spreadToken) { l.emit(itemSpread) return lexRoot } } fallthrough // '.' can start a number. case r == '+' || r == '-' || ('0' <= r && r <= '9'): l.backup() return lexNumber case isAlphaNumeric(r): l.backup() return lexName default: return l.errorf("unrecognized character in action: %#U", r) } return lexRoot } // lexName scans a name. func lexName(l *lexer) stateFn { for { r := l.next() if r == eof { l.emit(itemEOF) return nil } if !isAlphaNumeric(r) { l.backup() s, e := l.current() lowercase(l.input, s, e) switch { case equals(l.input, s, e, queryToken): l.emit(itemQuery) case equals(l.input, s, e, mutationToken): l.emit(itemMutation) case equals(l.input, s, e, subscriptionToken): l.emit(itemSub) case equals(l.input, s, e, trueToken): l.emit(itemBoolVal) case equals(l.input, s, e, falseToken): l.emit(itemBoolVal) default: l.emit(itemName) } break } } return lexRoot } // lexString scans a string. func lexString(l *lexer) stateFn { if l.accept([]byte(quotesToken)) { l.ignore() for { r := l.next() if r == eof { l.emit(itemEOF) return nil } if r == '\'' || r == '"' { l.backup() l.emit(itemStringVal) if l.accept(quotesToken) { l.ignore() } break } } } return lexRoot } // lexNumber scans a number: decimal, octal, hex, float, or imaginary. This // isn't a perfect number scanner - for instance it accepts "." and "0x0.2" // and "089" - but when it's wrong the input is invalid and the parser (via // strconv) will notice. func lexNumber(l *lexer) stateFn { var it itemType // Optional leading sign. l.accept(signsToken) // Is it integer if l.accept(digitToken) { l.acceptRun(digitToken) it = itemIntVal } // Is it float if l.peek() == '.' { if l.accept(dotToken) { if l.accept(digitToken) { l.acceptRun(digitToken) it = itemFloatVal } } else { l.backup() } } // Next thing mustn't be alphanumeric. if isAlphaNumeric(l.peek()) { l.next() return l.errorf("bad number syntax: %q", l.input[l.start:l.pos]) } if it != 0 { l.emit(it) } return lexRoot } // isSpace reports whether r is a space character. func isSpace(r rune) bool { return r == ',' || r == ' ' || r == '\t' } // isEndOfLine reports whether r is an end-of-line character. func isEndOfLine(r rune) bool { return r == '\r' || r == '\n' || r == eof } // isAlphaNumeric reports whether r is an alphabetic, digit, or underscore. func isAlphaNumeric(r rune) bool { return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r) } func equals(b []byte, s Pos, e Pos, val []byte) bool { n := 0 for i := s; i < e; i++ { if n >= len(val) { return true } switch { case b[i] >= 'A' && b[i] <= 'Z' && ('a'+(b[i]-'A')) != val[n]: return false case b[i] != val[n]: return false } n++ } return true } func contains(b []byte, s Pos, e Pos, val []byte) bool { for i := s; i < e; i++ { for n := 0; n < len(val); n++ { if b[i] == val[n] { return true } } } return false } func lowercase(b []byte, s Pos, e Pos) { for i := s; i < e; i++ { if b[i] >= 'A' && b[i] <= 'Z' { b[i] = ('a' + (b[i] - 'A')) } } } func (i *item) String() string { var v string switch i.typ { case itemEOF: v = "EOF" case itemError: v = "error" case itemName: v = "name" case itemQuery: v = "query" case itemMutation: v = "mutation" case itemSub: v = "subscription" case itemPunctuator: v = "punctuator" case itemDirective: v = "directive" case itemVariable: v = "variable" case itemIntVal: v = "int" case itemFloatVal: v = "float" case itemStringVal: v = "string" } return v } /* Copyright (c) 2009 The Go Authors. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Google Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */