Improve the way state is tracked in fillReadBuffer

1 files changed, 103 insertions, 74 deletions

diff --git a/walk/read.go b/walk/read.go
index 00be010..f123369 100644
--- a/walk/read.go
+++ b/walk/read.go
@@ -22,16 +22,22 @@ const (
 	JSONInRoot JSONInStructure = iota
 	JSONInMap
 	JSONInArray
+)
+
+type JSONInState int
+const (
+	JSONInValueEnd JSONInState = iota
+	JSONInValue
+	JSONInValueStart
 	JSONInString
-	JSONInValueEnd
 	JSONInKey
-	JSONInKeyEnd
 )
 
 type JSONIn struct {
 	path []Atom
 	reader *bufio.Reader
 	structure []JSONInStructure
+	state JSONInState
 	readBuffer []Atom
 	readIndex int
 	readBufferCapacity int
@@ -44,6 +50,7 @@ func NewJSONIn(reader *bufio.Reader) JSONIn {
 		path: make([]Atom, 0, 256),
 		reader: reader,
 		structure: []JSONInStructure{JSONInRoot},
+		state: JSONInValueStart,
 		readBuffer: make([]Atom, 0, 256),
 		readIndex: 0,
 		readBufferCapacity: 256,
@@ -142,8 +149,7 @@ func (in *JSONIn) Read() (WalkItem, error) {
 			in.readIndex = 0
 			in.actionBuffer = in.actionBuffer[:0]
 			in.readBuffer = in.readBuffer[:0]
-			structure, err := in.fillReadBuffer(in.structure)
-			in.structure = structure
+			err := in.fillReadBuffer()
 			if len(in.actionBuffer) == 0 {
 				return WalkItem{}, err
 			}
@@ -158,8 +164,7 @@ func (in *JSONIn) Read() (WalkItem, error) {
 						in.readBufferCapacity *= 2
 						copy(newReadBuffer, in.readBuffer)
 						in.readBuffer = newReadBuffer
-						structure, _ := in.fillReadBuffer(in.structure)
-						in.structure = structure
+						in.fillReadBuffer()
 						continue actionLoop
 					}
 					copy(in.readBuffer, in.readBuffer[in.readIndex:])
@@ -168,8 +173,7 @@ func (in *JSONIn) Read() (WalkItem, error) {
 					copy(in.actionBuffer, in.actionBuffer[in.actionIndex:])
 					in.actionBuffer = in.actionBuffer[:len(in.actionBuffer) - in.actionIndex]
 					in.actionIndex = 0
-					structure, _ := in.fillReadBuffer(in.structure)
-					in.structure = structure
+					in.fillReadBuffer()
 					continue actionLoop
 				}
 				in.readIndex += len(value)
@@ -186,8 +190,7 @@ func (in *JSONIn) Read() (WalkItem, error) {
 						in.readBufferCapacity *= 2
 						copy(newReadBuffer, in.readBuffer)
 						in.readBuffer = newReadBuffer
-						structure, _ := in.fillReadBuffer(in.structure)
-						in.structure = structure
+						in.fillReadBuffer()
 						continue actionLoop
 					}
 					copy(in.readBuffer, in.readBuffer[in.readIndex:])
@@ -196,8 +199,7 @@ func (in *JSONIn) Read() (WalkItem, error) {
 					copy(in.actionBuffer, in.actionBuffer[in.actionIndex:])
 					in.actionBuffer = in.actionBuffer[:len(in.actionBuffer) - in.actionIndex]
 					in.actionIndex = 0
-					structure, _ := in.fillReadBuffer(in.structure)
-					in.structure = structure
+					in.fillReadBuffer()
 					continue actionLoop
 				}
 				in.readIndex += len(value)
@@ -239,28 +241,34 @@ func (in *JSONIn) pushActionBuffer(action ReadAction) {
 	in.actionBuffer = append(in.actionBuffer, action)
 }
 
-func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure, error) {
+// Appends to the readBuffer until it has reached capacity
+// Also appends to the actionBuffer as needed
+func (in *JSONIn) fillReadBuffer() error {
+	switch in.state {
+		case JSONInValueStart:
+			goto valueStart
+		case JSONInValue:
+			goto value
+		case JSONInValueEnd:
+			goto valueEnd
+		case JSONInString:
+			goto string
+		case JSONInKey:
+			goto key
+		default:
+			panic("Invalid JSONInState")
+	}
 	valueStart: {
-		state := structure[len(structure) - 1]
-		switch state {
-			case JSONInString:
-				structure = structure[:len(structure) - 1]
-				goto string
-			case JSONInValueEnd:
-				structure = structure[:len(structure) - 1]
-				goto valueEnd
-			case JSONInKey:
-				structure = structure[:len(structure) - 1]
-				goto key
-			case JSONInKeyEnd:
-				structure = structure[:len(structure) - 1]
-				goto keyEnd
+		innermost := in.structure[len(in.structure) - 1]
+		switch innermost {
 			case JSONInMap:
 				goto mapValue
 			case JSONInArray:
 				goto arrayValue
 			case JSONInRoot:
 				goto value
+			default:
+				panic("Invalid JSONInStructure")
 		}
 	}
 	value: {
@@ -273,43 +281,49 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 				in.requireString("ull")
 				in.pushActionBuffer(ActionReadValue)
 				if in.pushReadBuffer(NewAtomNull()) {
-					return append(structure, JSONInValueEnd), nil
+					in.state = JSONInValueEnd
+					return nil
 				}
 				goto valueEnd
 			case 'f':
 				in.requireString("alse")
 				in.pushActionBuffer(ActionReadValue)
 				if in.pushReadBuffer(NewAtomBool(false)) {
-					return append(structure, JSONInValueEnd), nil
+					in.state = JSONInValueEnd
+					return nil
 				}
 				goto valueEnd
 			case 't':
 				in.requireString("rue")
 				in.pushActionBuffer(ActionReadValue)
 				if in.pushReadBuffer(NewAtomBool(true)) {
-					return append(structure, JSONInValueEnd), nil
+					in.state = JSONInValueEnd
+					return nil
 				}
 				goto valueEnd
 			case '"':
 				in.pushActionBuffer(ActionReadValue)
 				if in.pushReadBuffer(NewAtomStringTerminal()) {
-					return append(structure, JSONInString), nil
+					in.state = JSONInString
+					return nil
 				}
 				goto string
 			case '{':
-				structure = append(structure, JSONInMap)
+				in.structure = append(in.structure, JSONInMap)
 				in.pushActionBuffer(ActionReadValue)
 				in.pushActionBuffer(ActionAppendPathNull)
 				if in.pushReadBuffer(NewAtomTerminal(MapBegin)) {
-					return structure, nil
+					in.state = JSONInValueStart
+					return nil
 				}
 				goto mapValue
 			case '[':
-				structure = append(structure, JSONInArray)
+				in.structure = append(in.structure, JSONInArray)
 				in.pushActionBuffer(ActionReadValue)
 				in.pushActionBuffer(ActionAppendPathNull)
 				if in.pushReadBuffer(NewAtomTerminal(ArrayBegin)) {
-					return structure, nil
+					in.state = JSONInValueStart
+					return nil
 				}
 				goto arrayValue
 		}
@@ -333,7 +347,8 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 			}
 			in.pushActionBuffer(ActionReadValue)
 			if in.pushReadBuffer(NewAtomNumber(number)) {
-				return append(structure, JSONInValueEnd), nil
+				in.state = JSONInValueEnd
+				return nil
 			}
 			goto valueEnd
 		}
@@ -346,7 +361,8 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 		}
 		if r == '"' {
 			if in.pushReadBuffer(NewAtomStringTerminal()) {
-				return append(structure, JSONInValueEnd), nil
+				in.state = JSONInValueEnd
+				return nil
 			}
 			goto valueEnd
 		}
@@ -356,42 +372,45 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 				panic("Missing rune after \\")
 			}
 			if in.pushReadBuffer(NewAtomStringRune(r)) {
-				return append(structure, JSONInString), nil
+				in.state = JSONInString
+				return nil
 			}
 			goto string
 		}
 		if in.pushReadBuffer(NewAtomStringRune(r)) {
-			return append(structure, JSONInString), nil
+			in.state = JSONInString
+			return nil
 		}
 		goto string
 	}
 	key: {
-		r, _, err := in.reader.ReadRune()
-		if err != nil {
-			panic("Missing closing terminal in string input: " + err.Error())
-		}
-		if r == '"' {
-			if in.pushReadBuffer(NewAtomStringTerminal()) {
-				return append(structure, JSONInKeyEnd), nil
-			}
-			goto keyEnd
-		}
-		if r == '\\' {
-			r, _, err = in.reader.ReadRune()
+		var full bool
+		for {
+			r, _, err := in.reader.ReadRune()
 			if err != nil {
-				panic("Missing rune after \\")
+				panic("Missing closing terminal in string input: " + err.Error())
+			}
+			if r == '"' {
+				full = in.pushReadBuffer(NewAtomStringTerminal())
+				break
+			}
+			if r == '\\' {
+				r, _, err = in.reader.ReadRune()
+				if err != nil {
+					panic("Missing rune after \\")
+				}
+				if in.pushReadBuffer(NewAtomStringRune(r)) {
+					in.state = JSONInKey
+					return nil
+				}
+				continue
 			}
 			if in.pushReadBuffer(NewAtomStringRune(r)) {
-				return append(structure, JSONInKey), nil
+				in.state = JSONInKey
+				return nil
 			}
-			goto key
-		}
-		if in.pushReadBuffer(NewAtomStringRune(r)) {
-			return append(structure, JSONInKey), nil
+			continue
 		}
-		goto key
-	}
-	keyEnd: {
 		r, err := in.nextNonWsRune()
 		if err != nil {
 			panic("Expected : got: " + err.Error())
@@ -399,30 +418,37 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 		if r != ':' {
 			panic("Expected : after key")
 		}
+		if full {
+			in.state = JSONInValue
+			return nil
+		}
 		goto value
 	}
 	valueEnd: {
 		r, err := in.nextNonWsRune()
 		if err != nil {
-			return append(structure, JSONInValueEnd), err
+			in.state = JSONInValueEnd
+			return err
 		}
-		underState := structure[len(structure) - 1]
-		if underState == JSONInRoot {
+		innermost := in.structure[len(in.structure) - 1]
+		if innermost == JSONInRoot {
 			panic("More input after root JSON object ends")
-		} else if underState == JSONInMap && r == '}' {
-			structure = structure[:len(structure) - 1]
+		} else if innermost == JSONInMap && r == '}' {
+			in.structure = in.structure[:len(in.structure) - 1]
 			in.pushActionBuffer(ActionPopPath)
 			in.pushActionBuffer(ActionReadValue)
 			if in.pushReadBuffer(NewAtomTerminal(MapEnd)) {
-				return append(structure, JSONInValueEnd), nil
+				in.state = JSONInValueEnd
+				return nil
 			}
 			goto valueEnd
-		} else if underState == JSONInArray && r == ']' {
-			structure = structure[:len(structure) - 1]
+		} else if innermost == JSONInArray && r == ']' {
+			in.structure = in.structure[:len(in.structure) - 1]
 			in.pushActionBuffer(ActionPopPath)
 			in.pushActionBuffer(ActionReadValue)
 			if in.pushReadBuffer(NewAtomTerminal(ArrayEnd)) {
-				return append(structure, JSONInValueEnd), nil
+				in.state = JSONInValueEnd
+				return nil
 			}
 			goto valueEnd
 		}
@@ -438,10 +464,11 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 			panic("Missing value inside object")
 		}
 		if r == '}' {
-			structure = structure[:len(structure) - 1]
+			in.structure = in.structure[:len(in.structure) - 1]
 			in.pushActionBuffer(ActionReadValue)
 			if in.pushReadBuffer(NewAtomTerminal(MapEnd)) {
-				return append(structure, JSONInValueEnd), nil
+				in.state = JSONInValueEnd
+				return nil
 			}
 			goto valueEnd
 		}
@@ -450,7 +477,8 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 		}
 		in.pushActionBuffer(ActionAppendPath)
 		if in.pushReadBuffer(NewAtomStringTerminal()) {
-			return append(structure, JSONInKey), nil
+			in.state = JSONInKey
+			return nil
 		}
 		goto key
 	}
@@ -460,11 +488,12 @@ func (in *JSONIn) fillReadBuffer(structure []JSONInStructure) ([]JSONInStructure
 			panic("Missing value inside array")
 		}
 		if r == ']' {
-			structure = structure[:len(structure) - 1]
+			in.structure = in.structure[:len(in.structure) - 1]
 			in.pushActionBuffer(ActionPopPath)
 			in.pushActionBuffer(ActionReadValue)
 			if in.pushReadBuffer(NewAtomTerminal(ArrayEnd)) {
-				return append(structure, JSONInValueEnd), nil
+				in.state = JSONInValueEnd
+				return nil
 			}
 			goto valueEnd
 		}