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|
package json
import (
"bufio"
"fmt"
"main/walk"
)
func isNumber(value walk.Value) bool {
_, isFloat := value.(walk.NumberScalar)
return isFloat
}
func isString(value walk.Value) bool {
_, isString := value.(walk.StringStructure)
return isString
}
func segmentEqual(left walk.Value, right walk.Value) bool {
switch left := left.(type) {
case walk.NumberScalar:
_, isNumber := right.(walk.NumberScalar)
return isNumber
case walk.StringStructure:
right, isString := right.(walk.StringStructure)
return isString && left == right
default:
panic("Invalid path segment type")
}
}
type JSONWriterState int
const (
JSONWriterStateBeforeValue JSONWriterState = iota
JSONWriterStateAfterValue JSONWriterState = iota
JSONWriterStateInArray
JSONWriterStateInMap
)
func NewJSONWriter(writer *bufio.Writer) *JSONWriter {
return &JSONWriter {
path: nil,
writer: writer,
state: JSONWriterStateBeforeValue,
}
}
type JSONWriter struct {
path []walk.Value
writer *bufio.Writer
state JSONWriterState
}
func (writer *JSONWriter) Write(item walk.WalkItem) error {
path := item.Path
for _, value := range item.Value {
err := writer.write(path, value)
if err != nil {
return err
}
}
return nil
}
func (writer *JSONWriter) indent(level int) {
for i := 0; i < level; i += 1 {
writer.writer.WriteRune('\t')
}
}
func (writer *JSONWriter) write(targetPath []walk.Value, value walk.Value) error {
diversionPoint := len(writer.path)
for diversionPoint < len(writer.path) && diversionPoint < len(targetPath) && segmentEqual(writer.path[diversionPoint], targetPath[diversionPoint]) {
diversionPoint += 1
}
switch writer.state {
case JSONWriterStateBeforeValue:
goto beforeValue
case JSONWriterStateAfterValue:
goto afterValue
case JSONWriterStateInMap:
goto inMap
case JSONWriterStateInArray:
goto inArray
default:
panic("Invalid JSONWriterState")
}
beforeValue: {
switch value := value.(type) {
case walk.NullScalar:
writer.writer.WriteString("null")
writer.state = JSONWriterStateAfterValue
return nil
case walk.BoolScalar:
if value {
writer.writer.WriteString("true")
} else {
writer.writer.WriteString("false")
}
writer.state = JSONWriterStateAfterValue
return nil
case walk.NumberScalar:
writer.writer.WriteString(fmt.Sprintf("%v", value))
writer.state = JSONWriterStateAfterValue
return nil
case walk.StringStructure:
writer.writer.WriteString(fmt.Sprintf("%q", value))
writer.state = JSONWriterStateAfterValue
return nil
case walk.ArrayStructure:
// TODO: write the contents of the structures
writer.writer.WriteString("[\n")
writer.state = JSONWriterStateInArray
return nil
case walk.MapStructure:
writer.writer.WriteString("{\n")
writer.state = JSONWriterStateInMap
return nil
default:
panic("Invalid value type")
}
}
afterValue: {
if len(writer.path) == 0 {
writer.writer.WriteRune('\n')
goto beforeValue
}
switch writer.path[len(writer.path) - 1].(type) {
case walk.NumberScalar:
// TODO: second part of this condition might be redundant
if len(writer.path) - 1 <= diversionPoint && len(targetPath) >= len(writer.path) && isNumber(targetPath[len(writer.path) - 1]) {
writer.writer.WriteString(",\n")
writer.path = writer.path[:len(writer.path) - 1]
goto inArray
} else {
writer.writer.WriteString("\n")
writer.indent(len(writer.path) - 1)
writer.writer.WriteString("]")
writer.path = writer.path[:len(writer.path) - 1]
goto afterValue
}
case walk.StringStructure:
if len(writer.path) -1 <= diversionPoint && len(targetPath) >= len(writer.path) && isString(targetPath[len(writer.path) - 1]) {
writer.writer.WriteString(",\n")
writer.path = writer.path[:len(writer.path) - 1]
goto inMap
} else {
writer.writer.WriteString("\n")
writer.indent(len(writer.path) - 1)
writer.writer.WriteString("}")
writer.path = writer.path[:len(writer.path) - 1]
goto afterValue
}
default:
panic("Invalid path segment type")
}
}
inMap: {
if len(writer.path) <= diversionPoint && len(targetPath) > len(writer.path) && isString(targetPath[len(writer.path)]) {
writer.indent(len(writer.path) + 1)
writer.writer.WriteString(fmt.Sprintf("%q: ", targetPath[len(writer.path)].(walk.StringStructure)))
writer.path = append(writer.path, targetPath[len(writer.path)].(walk.StringStructure))
goto beforeValue
} else {
writer.writer.WriteString("\n}")
goto afterValue
}
}
inArray: {
if len(writer.path) <= diversionPoint && len(targetPath) > len(writer.path) && isNumber(targetPath[len(writer.path)]) {
writer.indent(len(writer.path) + 1)
writer.path = append(writer.path, walk.NumberScalar(0))
goto beforeValue
} else {
writer.writer.WriteString("\n]")
goto afterValue
}
}
}
func (writer *JSONWriter) AssertDone() {
for i := len(writer.path) - 1; i >= 0; i -= 1 {
switch writer.path[i].(type) {
case walk.NumberScalar:
writer.writer.WriteString("\n")
writer.indent(i)
writer.writer.WriteString("]")
case walk.StringStructure:
writer.writer.WriteString("\n")
writer.indent(i)
writer.writer.WriteString("}")
default:
panic("Invalid path segment type")
}
}
writer.writer.Flush()
}
|
