1 files changed, 291 insertions, 0 deletions
diff --git a/core/asm/lexer.go b/core/asm/lexer.go
new file mode 100644
index 000000000..2770bd35f
--- /dev/null
+++ b/core/asm/lexer.go
@@ -0,0 +1,291 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package asm
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// stateFn is used through the lifetime of the
+// lexer to parse the different values at the
+// current state.
+type stateFn func(*lexer) stateFn
+
+// token is emitted when the lexer has discovered
+// a new parsable token. These are delivered over
+// the tokens channels of the lexer
+type token struct {
+	typ    tokenType
+	lineno int
+	text   string
+}
+
+// tokenType are the different types the lexer
+// is able to parse and return.
+type tokenType int
+
+const (
+	eof              tokenType = iota // end of file
+	lineStart                         // emitted when a line starts
+	lineEnd                           // emitted when a line ends
+	invalidStatement                  // any invalid statement
+	element                           // any element during element parsing
+	label                             // label is emitted when a labal is found
+	labelDef                          // label definition is emitted when a new label is found
+	number                            // number is emitted when a number is found
+	stringValue                       // stringValue is emitted when a string has been found
+
+	Numbers            = "1234567890"                                           // characters representing any decimal number
+	HexadecimalNumbers = Numbers + "aAbBcCdDeEfF"                               // characters representing any hexadecimal
+	Alpha              = "abcdefghijklmnopqrstuwvxyzABCDEFGHIJKLMNOPQRSTUWVXYZ" // characters representing alphanumeric
+)
+
+// String implements stringer
+func (it tokenType) String() string {
+	if int(it) > len(stringtokenTypes) {
+		return "invalid"
+	}
+	return stringtokenTypes[it]
+}
+
+var stringtokenTypes = []string{
+	eof:              "EOF",
+	invalidStatement: "invalid statement",
+	element:          "element",
+	lineEnd:          "end of line",
+	lineStart:        "new line",
+	label:            "label",
+	labelDef:         "label definition",
+	number:           "number",
+	stringValue:      "string",
+}
+
+// lexer is the basic construct for parsing
+// source code and turning them in to tokens.
+// Tokens are interpreted by the compiler.
+type lexer struct {
+	input string // input contains the source code of the program
+
+	tokens chan token // tokens is used to deliver tokens to the listener
+	state  stateFn    // the current state function
+
+	lineno            int // current line number in the source file
+	start, pos, width int // positions for lexing and returning value
+
+	debug bool // flag for triggering debug output
+}
+
+// lex lexes the program by name with the given source. It returns a
+// channel on which the tokens are delivered.
+func Lex(name string, source []byte, debug bool) <-chan token {
+	ch := make(chan token)
+	l := &lexer{
+		input:  string(source),
+		tokens: ch,
+		state:  lexLine,
+		debug:  debug,
+	}
+	go func() {
+		l.emit(lineStart)
+		for l.state != nil {
+			l.state = l.state(l)
+		}
+		l.emit(eof)
+		close(l.tokens)
+	}()
+
+	return ch
+}
+
+// next returns the next rune in the program's source.
+func (l *lexer) next() (rune rune) {
+	if l.pos >= len(l.input) {
+		l.width = 0
+		return 0
+	}
+	rune, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
+	l.pos += l.width
+	return rune
+}
+
+// backup backsup the last parsed element (multi-character)
+func (l *lexer) backup() {
+	l.pos -= l.width
+}
+
+// peek returns the next rune but does not advance the seeker
+func (l *lexer) peek() rune {
+	r := l.next()
+	l.backup()
+	return r
+}
+
+// ignore advances the seeker and ignores the value
+func (l *lexer) ignore() {
+	l.start = l.pos
+}
+
+// Accepts checks whether the given input matches the next rune
+func (l *lexer) accept(valid string) bool {
+	if strings.IndexRune(valid, l.next()) >= 0 {
+		return true
+	}
+
+	l.backup()
+
+	return false
+}
+
+// acceptRun will continue to advance the seeker until valid
+// can no longer be met.
+func (l *lexer) acceptRun(valid string) {
+	for strings.IndexRune(valid, l.next()) >= 0 {
+	}
+	l.backup()
+}
+
+// acceptRunUntil is the inverse of acceptRun and will continue
+// to advance the seeker until the rune has been found.
+func (l *lexer) acceptRunUntil(until rune) bool {
+	// Continues running until a rune is found
+	for i := l.next(); strings.IndexRune(string(until), i) == -1; i = l.next() {
+		if i == 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
+// blob returns the current value
+func (l *lexer) blob() string {
+	return l.input[l.start:l.pos]
+}
+
+// Emits a new token on to token channel for processing
+func (l *lexer) emit(t tokenType) {
+	token := token{t, l.lineno, l.blob()}
+
+	if l.debug {
+		fmt.Fprintf(os.Stderr, "%04d: (%-20v) %s\n", token.lineno, token.typ, token.text)
+	}
+
+	l.tokens <- token
+	l.start = l.pos
+}
+
+// lexLine is state function for lexing lines
+func lexLine(l *lexer) stateFn {
+	for {
+		switch r := l.next(); {
+		case r == '\n':
+			l.emit(lineEnd)
+			l.ignore()
+			l.lineno++
+
+			l.emit(lineStart)
+		case r == ';' && l.peek() == ';':
+			return lexComment
+		case isSpace(r):
+			l.ignore()
+		case isAlphaNumeric(r) || r == '_':
+			return lexElement
+		case isNumber(r):
+			return lexNumber
+		case r == '@':
+			l.ignore()
+			return lexLabel
+		case r == '"':
+			return lexInsideString
+		default:
+			return nil
+		}
+	}
+}
+
+// lexComment parses the current position until the end
+// of the line and discards the text.
+func lexComment(l *lexer) stateFn {
+	l.acceptRunUntil('\n')
+	l.ignore()
+
+	return lexLine
+}
+
+// lexLabel parses the current label, emits and returns
+// the lex text state function to advance the parsing
+// process.
+func lexLabel(l *lexer) stateFn {
+	l.acceptRun(Alpha + "_")
+
+	l.emit(label)
+
+	return lexLine
+}
+
+// lexInsideString lexes the inside of a string until
+// until the state function finds the closing quote.
+// It returns the lex text state function.
+func lexInsideString(l *lexer) stateFn {
+	if l.acceptRunUntil('"') {
+		l.emit(stringValue)
+	}
+
+	return lexLine
+}
+
+func lexNumber(l *lexer) stateFn {
+	acceptance := Numbers
+	if l.accept("0") && l.accept("xX") {
+		acceptance = HexadecimalNumbers
+	}
+	l.acceptRun(acceptance)
+
+	l.emit(number)
+
+	return lexLine
+}
+
+func lexElement(l *lexer) stateFn {
+	l.acceptRun(Alpha + "_" + Numbers)
+
+	if l.peek() == ':' {
+		l.emit(labelDef)
+
+		l.accept(":")
+		l.ignore()
+	} else {
+		l.emit(element)
+	}
+	return lexLine
+}
+
+func isAlphaNumeric(t rune) bool {
+	return unicode.IsLetter(t)
+}
+
+func isSpace(t rune) bool {
+	return unicode.IsSpace(t)
+}
+
+func isNumber(t rune) bool {
+	return unicode.IsNumber(t)
+}