diff options
Diffstat (limited to 'vendor/github.com/graph-gophers/graphql-go/internal/common/lexer.go')
-rw-r--r-- | vendor/github.com/graph-gophers/graphql-go/internal/common/lexer.go | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/vendor/github.com/graph-gophers/graphql-go/internal/common/lexer.go b/vendor/github.com/graph-gophers/graphql-go/internal/common/lexer.go new file mode 100644 index 00000000..ff45bcad --- /dev/null +++ b/vendor/github.com/graph-gophers/graphql-go/internal/common/lexer.go @@ -0,0 +1,229 @@ +package common + +import ( + "bytes" + "fmt" + "strconv" + "strings" + "text/scanner" + + "github.com/graph-gophers/graphql-go/errors" + "github.com/graph-gophers/graphql-go/types" +) + +type syntaxError string + +type Lexer struct { + sc *scanner.Scanner + next rune + comment bytes.Buffer + useStringDescriptions bool +} + +type Ident struct { + Name string + Loc errors.Location +} + +func NewLexer(s string, useStringDescriptions bool) *Lexer { + sc := &scanner.Scanner{ + Mode: scanner.ScanIdents | scanner.ScanInts | scanner.ScanFloats | scanner.ScanStrings, + } + sc.Init(strings.NewReader(s)) + + l := Lexer{sc: sc, useStringDescriptions: useStringDescriptions} + l.sc.Error = l.CatchScannerError + + return &l +} + +func (l *Lexer) CatchSyntaxError(f func()) (errRes *errors.QueryError) { + defer func() { + if err := recover(); err != nil { + if err, ok := err.(syntaxError); ok { + errRes = errors.Errorf("syntax error: %s", err) + errRes.Locations = []errors.Location{l.Location()} + return + } + panic(err) + } + }() + + f() + return +} + +func (l *Lexer) Peek() rune { + return l.next +} + +// ConsumeWhitespace consumes whitespace and tokens equivalent to whitespace (e.g. commas and comments). +// +// Consumed comment characters will build the description for the next type or field encountered. +// The description is available from `DescComment()`, and will be reset every time `ConsumeWhitespace()` is +// executed unless l.useStringDescriptions is set. +func (l *Lexer) ConsumeWhitespace() { + l.comment.Reset() + for { + l.next = l.sc.Scan() + + if l.next == ',' { + // Similar to white space and line terminators, commas (',') are used to improve the + // legibility of source text and separate lexical tokens but are otherwise syntactically and + // semantically insignificant within GraphQL documents. + // + // http://facebook.github.io/graphql/draft/#sec-Insignificant-Commas + continue + } + + if l.next == '#' { + // GraphQL source documents may contain single-line comments, starting with the '#' marker. + // + // A comment can contain any Unicode code point except `LineTerminator` so a comment always + // consists of all code points starting with the '#' character up to but not including the + // line terminator. + l.consumeComment() + continue + } + + break + } +} + +// consumeDescription optionally consumes a description based on the June 2018 graphql spec if any are present. +// +// Single quote strings are also single line. Triple quote strings can be multi-line. Triple quote strings +// whitespace trimmed on both ends. +// If a description is found, consume any following comments as well +// +// http://facebook.github.io/graphql/June2018/#sec-Descriptions +func (l *Lexer) consumeDescription() string { + // If the next token is not a string, we don't consume it + if l.next != scanner.String { + return "" + } + // Triple quote string is an empty "string" followed by an open quote due to the way the parser treats strings as one token + var desc string + if l.sc.Peek() == '"' { + desc = l.consumeTripleQuoteComment() + } else { + desc = l.consumeStringComment() + } + l.ConsumeWhitespace() + return desc +} + +func (l *Lexer) ConsumeIdent() string { + name := l.sc.TokenText() + l.ConsumeToken(scanner.Ident) + return name +} + +func (l *Lexer) ConsumeIdentWithLoc() types.Ident { + loc := l.Location() + name := l.sc.TokenText() + l.ConsumeToken(scanner.Ident) + return types.Ident{Name: name, Loc: loc} +} + +func (l *Lexer) ConsumeKeyword(keyword string) { + if l.next != scanner.Ident || l.sc.TokenText() != keyword { + l.SyntaxError(fmt.Sprintf("unexpected %q, expecting %q", l.sc.TokenText(), keyword)) + } + l.ConsumeWhitespace() +} + +func (l *Lexer) ConsumeLiteral() *types.PrimitiveValue { + lit := &types.PrimitiveValue{Type: l.next, Text: l.sc.TokenText()} + l.ConsumeWhitespace() + return lit +} + +func (l *Lexer) ConsumeToken(expected rune) { + if l.next != expected { + l.SyntaxError(fmt.Sprintf("unexpected %q, expecting %s", l.sc.TokenText(), scanner.TokenString(expected))) + } + l.ConsumeWhitespace() +} + +func (l *Lexer) DescComment() string { + comment := l.comment.String() + desc := l.consumeDescription() + if l.useStringDescriptions { + return desc + } + return comment +} + +func (l *Lexer) SyntaxError(message string) { + panic(syntaxError(message)) +} + +func (l *Lexer) Location() errors.Location { + return errors.Location{ + Line: l.sc.Line, + Column: l.sc.Column, + } +} + +func (l *Lexer) consumeTripleQuoteComment() string { + l.next = l.sc.Next() + if l.next != '"' { + panic("consumeTripleQuoteComment used in wrong context: no third quote?") + } + + var buf bytes.Buffer + var numQuotes int + for { + l.next = l.sc.Next() + if l.next == '"' { + numQuotes++ + } else { + numQuotes = 0 + } + buf.WriteRune(l.next) + if numQuotes == 3 || l.next == scanner.EOF { + break + } + } + val := buf.String() + val = val[:len(val)-numQuotes] + return blockString(val) +} + +func (l *Lexer) consumeStringComment() string { + val, err := strconv.Unquote(l.sc.TokenText()) + if err != nil { + panic(err) + } + return val +} + +// consumeComment consumes all characters from `#` to the first encountered line terminator. +// The characters are appended to `l.comment`. +func (l *Lexer) consumeComment() { + if l.next != '#' { + panic("consumeComment used in wrong context") + } + + // TODO: count and trim whitespace so we can dedent any following lines. + if l.sc.Peek() == ' ' { + l.sc.Next() + } + + if l.comment.Len() > 0 { + l.comment.WriteRune('\n') + } + + for { + next := l.sc.Next() + if next == '\r' || next == '\n' || next == scanner.EOF { + break + } + l.comment.WriteRune(next) + } +} + +func (l *Lexer) CatchScannerError(s *scanner.Scanner, msg string) { + l.SyntaxError(msg) +} |