Refactor indent state (#481)

* refactor indent state

* refactor function position

* remove unnecessary function

lexer/lexer_test.go

@@ -22,7 +22,7 @@ func TestTokenize(t *testing.T) {
 					CharacterType: token.CharacterTypeMiscellaneous,
 					Indicator:     token.NotIndicator,
 					Value:         "null",
-					Origin:        "null\n",
+					Origin:        "null\n\t\t",
 				},
 			},
 		},
@@ -828,7 +828,7 @@ func TestTokenize(t *testing.T) {
 					CharacterType: token.CharacterTypeMiscellaneous,
 					Indicator:     token.NotIndicator,
 					Value:         "123",
-					Origin:        "123\n",
+					Origin:        "123\n\t\t",
 				},
 			},
 		},

parser/parser_test.go

@@ -439,6 +439,20 @@ a:
     piyo
 `,
 		},
+		{
+			`
+v: |
+ a
+ b
+ c`,
+			`
+v: |
+ a
+ b
+ c
+`,
+		},
+
 		{
 			`
 a: |

scanner/scanner.go

@@ -145,44 +145,31 @@ func (s *Scanner) updateIndentLevel() {
 	}
 }
 
-func (s *Scanner) indentStateFromIndentNumDifference() IndentState {
-	switch {
-	case s.prevLineIndentNum < s.indentNum:
-		return IndentStateUp
-	case s.prevLineIndentNum == s.indentNum:
-		return IndentStateEqual
-	default:
-		return IndentStateDown
-	}
-}
-
 func (s *Scanner) updateIndentState(ctx *Context) {
-	s.updateIndentLevel()
-
 	if s.lastDelimColumn > 0 {
 		if s.lastDelimColumn < s.column {
 			s.indentState = IndentStateUp
-		} else if s.lastDelimColumn != s.column || s.prevLineIndentNum != s.indentNum {
-			// The following case ( current position is 'd' ), some variables becomes like here
-			// - lastDelimColumn: 1 of 'a'
-			// - indentNumBasedIndentState: IndentStateDown because d's indentNum(1) is less than c's indentNum(3).
-			// Therefore, s.lastDelimColumn(1) == s.column(1) is true, but we want to treat this as IndentStateDown.
-			// So, we look also current indentState value by the above prevLineIndentNum based logic, and determines finally indentState.
-			// ---
-			// a:
-			//   b
-			//   c
-			// d: e
-			// ^
-			s.indentState = IndentStateDown
 		} else {
-			s.indentState = IndentStateEqual
+			// If lastDelimColumn and s.column are the same,
+			// treat as Down state since it is the same column as delimiter.
+			s.indentState = IndentStateDown
 		}
 	} else {
 		s.indentState = s.indentStateFromIndentNumDifference()
 	}
 }
 
+func (s *Scanner) indentStateFromIndentNumDifference() IndentState {
+	switch {
+	case s.prevLineIndentNum < s.indentNum:
+		return IndentStateUp
+	case s.prevLineIndentNum == s.indentNum:
+		return IndentStateEqual
+	default:
+		return IndentStateDown
+	}
+}
+
 func (s *Scanner) updateIndent(ctx *Context, c rune) {
 	if s.isFirstCharAtLine && s.isNewLineChar(c) && ctx.isDocument() {
 		return
@@ -195,6 +182,7 @@ func (s *Scanner) updateIndent(ctx *Context, c rune) {
 		s.indentState = IndentStateKeep
 		return
 	}
+	s.updateIndentLevel()
 	s.updateIndentState(ctx)
 	s.isFirstCharAtLine = false
 }
@@ -207,10 +195,6 @@ func (s *Scanner) isChangedToIndentStateUp() bool {
 	return s.indentState == IndentStateUp
 }
 
-func (s *Scanner) isChangedToIndentStateEqual() bool {
-	return s.indentState == IndentStateEqual
-}
-
 func (s *Scanner) addBufferedTokenIfExists(ctx *Context) {
 	ctx.addToken(s.bufferedToken(ctx))
 }
@@ -634,23 +618,16 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 		pos = ctx.nextPos()
 		c := ctx.currentChar()
 		s.updateIndent(ctx, c)
+		if s.isChangedToIndentStateDown() {
+			s.addBufferedTokenIfExists(ctx)
+		}
 		if ctx.isDocument() {
-			if (s.indentNum == 0 && s.isChangedToIndentStateEqual()) ||
-				s.isChangedToIndentStateDown() {
-				s.addBufferedTokenIfExists(ctx)
+			if s.isChangedToIndentStateDown() {
 				s.breakLiteral(ctx)
 			} else {
 				s.scanLiteral(ctx, c)
 				continue
 			}
-		} else if s.isChangedToIndentStateDown() {
-			s.addBufferedTokenIfExists(ctx)
-		} else if s.isChangedToIndentStateEqual() {
-			// if first character is new line character, buffer expect to raw folded literal
-			if len(ctx.obuf) > 0 && s.newLineCount(ctx.obuf) <= 1 {
-				// doesn't raw folded literal
-				s.addBufferedTokenIfExists(ctx)
-			}
 		}
 		switch c {
 		case '{':