diff options
Diffstat (limited to 'json_tokens/read.go')
| -rw-r--r-- | json_tokens/read.go | 490 |
1 files changed, 490 insertions, 0 deletions
diff --git a/json_tokens/read.go b/json_tokens/read.go new file mode 100644 index 0000000..95bbb9d --- /dev/null +++ b/json_tokens/read.go @@ -0,0 +1,490 @@ +package json_tokens + +import ( + "main/walk" + "bufio" + "strings" + "strconv" + "fmt" +) + +type ReadAction int +const ( + ActionReadValue ReadAction = iota + ActionAppendPath + ActionPopPath + ActionIncrementPath + ActionAppendPathNull +) + +type JSONInStructure int +const ( + JSONInMap JSONInStructure = iota + JSONInArray +) + +type JSONInState int +const ( + JSONInValueEnd JSONInState = iota + JSONInValue + JSONInValueStart + JSONInString + JSONInKey +) + +type JSONIn struct { + path []walk.Atom + reader *bufio.Reader + structure []JSONInStructure + state JSONInState + readBuffer []walk.Atom + readIndex int + readBufferCapacity int + actionBuffer []ReadAction + actionIndex int +} + +func NewJSONIn(reader *bufio.Reader) *JSONIn { + return &JSONIn { + path: make([]walk.Atom, 0, 256), + reader: reader, + structure: []JSONInStructure{}, + state: JSONInValueStart, + readBuffer: make([]walk.Atom, 0, 256), + readIndex: 0, + readBufferCapacity: 256, + actionBuffer: make([]ReadAction, 0, 256), + actionIndex: 0, + } +} + +func isWhitespace(r rune) bool { + for _, ws := range " \t\r\n" { + if r == ws { + return true + } + } + return false +} + +func isNumberRune(r rune) bool { + return '0' <= r && r <= '9' || r == '.' +} + +func (in *JSONIn) popPath() { + if len(in.path) == 0 { + panic("Tried to pop from empty path") + } + finalAtom := in.path[len(in.path) - 1] + if finalAtom.Typ != walk.AtomStringTerminal { + in.path = in.path[:len(in.path) - 1] + return + } + i := len(in.path) - 2 + for { + if i < 0 { + panic("Missing string begin in path") + } + if in.path[i].Typ == walk.AtomStringTerminal { + break + } + i-- + } + in.path = in.path[:i] +} + +func (in *JSONIn) nextNonWsRune() (rune, error) { + for { + r, _, err := in.reader.ReadRune() + if err != nil { + return 0, err + } + if !isWhitespace(r) { + return r, nil + } + } +} + +func (in *JSONIn) requireString(criteria string) { + for _, r := range criteria { + in.require(r) + } +} + +func (in *JSONIn) require(criterion rune) { + r, _, err := in.reader.ReadRune() + if err != nil { + panic("Error while reading required rune: " + err.Error()) + } + if r != criterion { + panic("Required rune not read") + } +} + +// Returns the first full value of a list of atoms and also a boolean to indicate if there isn't a value at the beginning +func firstValue(atoms []walk.Atom) ([]walk.Atom, bool) { + if len(atoms) == 0 { + return nil, true + } + if atoms[0].Typ != walk.AtomStringTerminal { + return atoms[0:1], false + } + i := 1 + for { + if i == len(atoms) { + return nil, true + } + if atoms[i].Typ == walk.AtomStringTerminal { + return atoms[0:i+1], false + } + i++ + } +} + +func (in *JSONIn) readValue() []walk.Atom { + try: + value, incomplete := firstValue(in.readBuffer[in.readIndex:]) + if incomplete { + if in.readIndex == 0 { + newReadBuffer := make([]walk.Atom, len(in.readBuffer), in.readBufferCapacity * 2) + in.readBufferCapacity *= 2 + copy(newReadBuffer, in.readBuffer) + in.readBuffer = newReadBuffer + in.fillReadBuffer() + goto try + } + copy(in.readBuffer, in.readBuffer[in.readIndex:]) + in.readBuffer = in.readBuffer[:len(in.readBuffer) - in.readIndex] + in.readIndex = 0 + copy(in.actionBuffer, in.actionBuffer[in.actionIndex:]) + in.actionBuffer = in.actionBuffer[:len(in.actionBuffer) - in.actionIndex] + in.actionIndex = 0 + in.fillReadBuffer() + goto try + } + in.readIndex += len(value) + return value +} + +func (in *JSONIn) Read() (walk.WalkItem, error) { + for { + if in.actionIndex == len(in.actionBuffer) { + in.actionIndex = 0 + in.readIndex = 0 + in.actionBuffer = in.actionBuffer[:0] + in.readBuffer = in.readBuffer[:0] + err := in.fillReadBuffer() + if len(in.actionBuffer) == 0 { + return walk.WalkItem{}, err + } + } + action := in.actionBuffer[in.actionIndex] + in.actionIndex++ + switch action { + case ActionReadValue: + value := in.readValue() + return walk.WalkItem { + Value: value, + Path: in.path, + }, nil + case ActionAppendPath: + value := in.readValue() + in.path = append(in.path, value...) + case ActionAppendPathNull: + in.path = append(in.path, walk.NewAtomNull()) + case ActionPopPath: + in.popPath() + case ActionIncrementPath: + prevIndex := in.path[len(in.path) - 1] + if prevIndex.Typ == walk.AtomNull { + prevIndex = walk.NewAtomNumber(0) + } else if prevIndex.Typ == walk.AtomNumber { + prevIndex = walk.NewAtomNumber(prevIndex.Number() + 1) + } else { + panic("Invalid index in array input. Type: " + fmt.Sprintf("%v", prevIndex.Typ)) + } + in.path[len(in.path) - 1] = prevIndex + default: + panic("Invalid ReadAction") + } + } +} + +func (in *JSONIn) AssertDone() { + if len(in.structure) != 0 || in.state != JSONInValueEnd || in.readIndex < len(in.readBuffer) { + panic("Input ended on incomplete JSON root") + } +} + +func (in *JSONIn) pushReadBuffer(atom walk.Atom) bool { + in.readBuffer = append(in.readBuffer, atom) + return len(in.readBuffer) == in.readBufferCapacity +} + +func (in *JSONIn) pushActionBuffer(action ReadAction) { + in.actionBuffer = append(in.actionBuffer, action) +} + +// 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: { + if len(in.structure) == 0 { + goto value + } + innermost := in.structure[len(in.structure) - 1] + switch innermost { + case JSONInMap: + goto mapValue + case JSONInArray: + goto arrayValue + default: + panic("Invalid JSONInStructure") + } + } + value: { + r, err := in.nextNonWsRune() + if err != nil { + panic("Missing value in JSON") + } + switch r { + case 'n': + in.requireString("ull") + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomNull()) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + case 'f': + in.requireString("alse") + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomBool(false)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + case 't': + in.requireString("rue") + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomBool(true)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + case '"': + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomStringTerminal()) { + in.state = JSONInString + return nil + } + goto string + case '{': + in.structure = append(in.structure, JSONInMap) + in.pushActionBuffer(ActionReadValue) + in.pushActionBuffer(ActionAppendPathNull) + if in.pushReadBuffer(walk.NewAtomTerminal(walk.MapBegin)) { + in.state = JSONInValueStart + return nil + } + goto mapValue + case '[': + in.structure = append(in.structure, JSONInArray) + in.pushActionBuffer(ActionReadValue) + in.pushActionBuffer(ActionAppendPathNull) + if in.pushReadBuffer(walk.NewAtomTerminal(walk.ArrayBegin)) { + in.state = JSONInValueStart + return nil + } + goto arrayValue + } + if isNumberRune(r) { + var builder strings.Builder + builder.WriteRune(r) + for { + r, _, err = in.reader.ReadRune() + if err != nil { + break + } + if !isNumberRune(r) { + in.reader.UnreadRune() + break + } + builder.WriteRune(r) + } + number, parseError := strconv.ParseFloat(builder.String(), 64) + if parseError != nil { + panic("Invalid number") + } + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomNumber(number)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + } + panic("Invalid JSON value starting with: " + string(r)) + } + string: { + r, _, err := in.reader.ReadRune() + if err != nil { + panic("Missing closing terminal in string input: " + err.Error()) + } + if r == '"' { + if in.pushReadBuffer(walk.NewAtomStringTerminal()) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + } + if r == '\\' { + r, _, err = in.reader.ReadRune() + if err != nil { + panic("Missing rune after \\") + } + if in.pushReadBuffer(walk.NewAtomStringRune(r)) { + in.state = JSONInString + return nil + } + goto string + } + if in.pushReadBuffer(walk.NewAtomStringRune(r)) { + in.state = JSONInString + return nil + } + goto string + } + key: { + var full bool + for { + r, _, err := in.reader.ReadRune() + if err != nil { + panic("Missing closing terminal in string input: " + err.Error()) + } + if r == '"' { + full = in.pushReadBuffer(walk.NewAtomStringTerminal()) + break + } + if r == '\\' { + r, _, err = in.reader.ReadRune() + if err != nil { + panic("Missing rune after \\") + } + if in.pushReadBuffer(walk.NewAtomStringRune(r)) { + in.state = JSONInKey + return nil + } + continue + } + if in.pushReadBuffer(walk.NewAtomStringRune(r)) { + in.state = JSONInKey + return nil + } + continue + } + r, err := in.nextNonWsRune() + if err != nil { + panic("Expected : got: " + err.Error()) + } + if r != ':' { + panic("Expected : after key") + } + if full { + in.state = JSONInValue + return nil + } + goto value + } + valueEnd: { + r, err := in.nextNonWsRune() + if err != nil { + in.state = JSONInValueEnd + return err + } + if len(in.structure) == 0 { + panic("More input after root JSON object ends") + } + innermost := in.structure[len(in.structure) - 1] + if innermost == JSONInMap && r == '}' { + in.structure = in.structure[:len(in.structure) - 1] + in.pushActionBuffer(ActionPopPath) + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomTerminal(walk.MapEnd)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + } else if innermost == JSONInArray && r == ']' { + in.structure = in.structure[:len(in.structure) - 1] + in.pushActionBuffer(ActionPopPath) + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomTerminal(walk.ArrayEnd)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + } + if r != ',' { + panic("Expected , after JSON value, found: \"" + string(r) + "\"") + } + goto valueStart + } + mapValue: { + in.pushActionBuffer(ActionPopPath) + r, err := in.nextNonWsRune() + if err != nil { + panic("Missing value inside object") + } + if r == '}' { + in.structure = in.structure[:len(in.structure) - 1] + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomTerminal(walk.MapEnd)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + } + if r != '"' { + panic("Expected key found something else") + } + in.pushActionBuffer(ActionAppendPath) + if in.pushReadBuffer(walk.NewAtomStringTerminal()) { + in.state = JSONInKey + return nil + } + goto key + } + arrayValue: { + r, err := in.nextNonWsRune() + if err != nil { + panic("Missing value inside array") + } + if r == ']' { + in.structure = in.structure[:len(in.structure) - 1] + in.pushActionBuffer(ActionPopPath) + in.pushActionBuffer(ActionReadValue) + if in.pushReadBuffer(walk.NewAtomTerminal(walk.ArrayEnd)) { + in.state = JSONInValueEnd + return nil + } + goto valueEnd + } + in.reader.UnreadRune() + in.pushActionBuffer(ActionIncrementPath) + goto value + } +} |