From cda08168736997efbb6b0e2c0ff32e6bc1a78f36 Mon Sep 17 00:00:00 2001
From: brettlangdon <brett@blangdon.com>
Date: Sun, 13 Sep 2015 22:29:16 -0400
Subject: [PATCH] start port of tokenizer over to scanner

---
 scanner/scanner.go | 170 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 162 insertions(+), 8 deletions(-)

diff --git a/scanner/scanner.go b/scanner/scanner.go
index 7fdb729..e1db326 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -33,7 +33,7 @@ func NewScanner(r io.Reader) *Scanner {
 
 func (scanner *Scanner) nextPosition() *Position {
 	if len(scanner.positionBuffer) > 0 {
-		last = len(scanner.positionBuffer) - 1
+		last := len(scanner.positionBuffer) - 1
 		scanner.currentPosition = scanner.positionBuffer[last]
 		scanner.positionBuffer = scanner.positionBuffer[0:last]
 		return scanner.currentPosition
@@ -43,27 +43,181 @@ func (scanner *Scanner) nextPosition() *Position {
 	if err != nil {
 		scanner.state = errorcode.E_EOF
 		next = EOF
-	}
-
-	scanner.currentColumn++
-	if next == '\n' {
 		scanner.currentLine++
 		scanner.currentColumn = 0
 	}
 
-	return &Position{
+	pos := &Position{
 		Char:   next,
 		Line:   scanner.currentLine,
 		Column: scanner.currentColumn,
 	}
+
+	scanner.currentColumn++
+	if next == '\n' || next == EOF {
+		scanner.currentLine++
+		scanner.currentColumn = 0
+	}
+
+	return pos
 }
 
 func (scanner *Scanner) unreadPosition(pos *Position) {
 	scanner.positionBuffer = append(scanner.positionBuffer, pos)
 }
 
+func (scanner *Scanner) parseQuoted(positions *Positions, quote rune) *token.Token {
+	// Determine quote size, 1 or 3 (e.g. 'string',  '''string''')
+	quoteSize := 1
+	endQuoteSize := 0
+	pos := scanner.nextPosition()
+	if pos.Char == quote {
+		pos2 := scanner.nextPosition()
+		if pos2.Char == quote {
+			positions.Append(pos)
+			positions.Append(pos2)
+			quoteSize = 3
+		} else {
+			scanner.unreadPosition(pos2)
+			endQuoteSize = 1
+		}
+	} else {
+		scanner.unreadPosition(pos)
+	}
+
+	for {
+		if endQuoteSize == quoteSize {
+			break
+		}
+		pos = scanner.nextPosition()
+		positions.Append(pos)
+		if pos.Char == EOF {
+			return positions.AsToken(token.ERRORTOKEN)
+		}
+		if quoteSize == 1 && pos.Char == '\n' {
+			return positions.AsToken(token.ERRORTOKEN)
+		}
+		if pos.Char == quote {
+			endQuoteSize += 1
+		} else {
+			endQuoteSize = 0
+			if pos.Char == '\\' {
+				pos = scanner.nextPosition()
+			}
+		}
+	}
+	return positions.AsToken(token.STRING)
+}
+
 func (scanner *Scanner) NextToken() *token.Token {
-	return &Token{
-		ID: token.ENDMARKER,
+	positions := NewPositions()
+
+	pos := scanner.nextPosition()
+	// skip spaces
+	for {
+		if pos.Char != ' ' && pos.Char != '\t' {
+			break
+		}
+		pos = scanner.nextPosition()
+	}
+
+	// skip comments
+	if pos.Char == '#' {
+		for {
+			pos = scanner.nextPosition()
+			if pos.Char == EOF || pos.Char == '\n' {
+				break
+			}
+		}
 	}
+
+	positions.Append(pos)
+	switch ch := pos.Char; {
+	case ch == EOF:
+		id := token.ENDMARKER
+		if scanner.state != errorcode.E_EOF {
+			id = token.ERRORTOKEN
+		}
+		return positions.AsToken(id)
+	case IsIdentifierStart(ch):
+		// Parse Identifier
+		saw_b, saw_r, saw_u := false, false, false
+		for {
+			if !(saw_b || saw_u) && (ch == 'b' || ch == 'B') {
+				saw_b = true
+			} else if !(saw_b || saw_u || saw_r) && (ch == 'u' || ch == 'U') {
+				saw_u = true
+			} else if !(saw_r || saw_u) && (ch == 'r' || ch == 'R') {
+				saw_r = true
+			} else {
+				break
+			}
+			pos = scanner.nextPosition()
+			if IsQuote(pos.Char) {
+				positions.Append(pos)
+				return scanner.parseQuoted(positions, pos.Char)
+			}
+		}
+		pos = scanner.nextPosition()
+		for IsIdentifierChar(pos.Char) {
+			positions.Append(pos)
+			pos = scanner.nextPosition()
+		}
+		scanner.unreadPosition(pos)
+		return positions.AsToken(token.NAME)
+	case ch == '\n':
+		return positions.AsToken(token.NEWLINE)
+	case ch == '.':
+		pos2 := scanner.nextPosition()
+		if IsDigit(pos2.Char) {
+			// Parse Number
+		} else if pos2.Char == '.' {
+			positions.Append(pos2)
+			pos3 := scanner.nextPosition()
+			if pos3.Char == '.' {
+				positions.Append(pos3)
+				return positions.AsToken(token.ELLIPSIS)
+			}
+			scanner.unreadPosition(pos3)
+		}
+		scanner.unreadPosition(pos2)
+
+		return positions.AsToken(token.DOT)
+	case IsDigit(ch):
+		// Parse Number
+	case IsQuote(ch):
+		// Parse String
+		return scanner.parseQuoted(positions, ch)
+	case ch == '\\':
+		// Parse Continuation
+	default:
+		// Two and Three character operators
+		pos2 := scanner.nextPosition()
+		op2Id := GetTwoCharTokenID(pos.Char, pos2.Char)
+		if op2Id != token.OP {
+			positions.Append(pos2)
+			pos3 := scanner.nextPosition()
+			op3Id := GetThreeCharTokenID(pos.Char, pos2.Char, pos3.Char)
+			if op3Id != token.OP {
+				positions.Append(pos3)
+				return positions.AsToken(op3Id)
+			}
+			scanner.unreadPosition(pos3)
+			return positions.AsToken(op2Id)
+		}
+		scanner.unreadPosition(pos2)
+	}
+	switch pos.Char {
+	case '(', '[', '{':
+		// Increment indentation level
+		// scanner.indentationLevel++
+		break
+	case ')', ']', '}':
+		// Decrement indentation level
+		// scanner.indentationLevel--
+		break
+	}
+
+	opId := GetOneCharTokenID(pos.Char)
+	return positions.AsToken(opId)
 }