ll1/flexgen/flexer_lexer.go

package flexer

const (
	FlexerKindDot = Kind(-1 - iota)
	FlexerKindLiteralString
	FlexerKindLiteralRaw
	FlexerKindLiteralChar
	FlexerKindTerminal
	FlexerKindArrow
	FlexerKindFlexerKeyword
	FlexerKindWhitespace
	FlexerKindLineComment
	FlexerKindBlockComment
	FlexerKindFlexerAction
)

/*

// Flexer generator's input own lexer specification
dot          	-> '\.' .
arrow        	-> "(?:->|→)" .
terminal     	-> "[[:isLower:]][[:isAlNum]_-]+" .
literal-string  -> `"` flex-esc-string  .
literal-raw     -> "`" flex-string  .
literal-char    -> "'" flex-string  .
flexer-keyword	-> "flex-skip|flex-string|flex-esc-string" .
whitespace   	-> "[ \t\n\r]+" flex-skip .
line-comment 	-> "//[^\n\r]+" flex-skip .
block-comment	-> "/\*(?ms:.)*?\* /" .
flexer-action   -> `%{(?ms:.)*?}%` .

*/

type CheckedError struct {
	Error error
}

func Check(err error) {
	if err != nil {
		panic(CheckedError{err})
	}
}

func LexFlexerInputString(name, input string) []Token {
	f := NewFlexer(name, input)
	Check(f.Rule(FlexerKindWhitespace, `[ \t\n\r]+`, "", nil))
	Check(f.Rule(FlexerKindLineComment, `//[^\n\r]+[\n\r]+`, "", nil))
	Check(f.Rule(FlexerKindBlockComment, `/\*(?ms:.)*?\*/`, "", nil))
	Check(f.Rule(FlexerKindDot, `\.`, "", nil))
	Check(f.Rule(FlexerKindArrow, `(?:->|→)`, "", nil))
	Check(f.Rule(FlexerKindTerminal, `[[:lower:]][[:alnum:]_-]+`, "", nil))
	f.EscapedStringRule(FlexerKindLiteralString, `"`, `"`, "literal-string")
	f.RawStringRule(FlexerKindLiteralRaw, "`", "`", "literal-raw")
	f.RawStringRule(FlexerKindLiteralChar, `''`, `''`, "literal-char")
	Check(f.Rule(FlexerKindFlexerKeyword, `flex-skip|flex-string|flex-esc-string`, "", nil))
	Check(f.Rule(FlexerKindFlexerAction, `@{(?ms:.)*?}@`, "", nil))

	skipKinds := []Kind{SkipKind, FlexerKindWhitespace, FlexerKindBlockComment, FlexerKindLineComment}

	return LexAll(f, skipKinds...)
}