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package json_array
import (
"bufio"
"strings"
"main/walk"
"encoding/json"
)
func assembleValue(atoms []walk.Atom) (interface{}, []walk.Atom) {
if len(atoms) == 0 {
panic("Missing JSON value in output")
}
switch atoms[0].Typ {
case walk.AtomNull:
return nil, atoms[1:]
case walk.AtomBool:
return atoms[0].Bool(), atoms[1:]
case walk.AtomNumber:
return atoms[0].Number(), atoms[1:]
case walk.AtomStringTerminal:
var builder strings.Builder
atoms = atoms[1:]
for {
if len(atoms) == 0 {
panic("Missing closing string terminal")
}
if atoms[0].Typ == walk.AtomStringTerminal {
break
}
if atoms[0].Typ != walk.AtomStringRune {
panic("Non string rune atom inside string")
}
builder.WriteRune(atoms[0].StringRune())
atoms = atoms[1:]
}
atoms = atoms[1:]
return builder.String(), atoms
case walk.AtomStringRune:
panic("String rune used outside of string terminals")
case walk.AtomTerminal:
terminal := atoms[0].Terminal()
switch terminal {
case walk.ArrayEnd, walk.MapEnd:
panic("Tried to extract value from end terminal")
case walk.ArrayBegin:
var arr []interface{}
var element interface{}
atoms = atoms[1:]
for {
if len(atoms) == 0 {
panic("Missing array end terminal")
}
if atoms[0].Typ == walk.AtomTerminal && atoms[0].Terminal() == walk.ArrayEnd {
atoms = atoms[1:]
break
}
element, atoms = assembleValue(atoms)
arr = append(arr, element)
}
return arr, atoms
case walk.MapBegin:
obj := make(map[string]interface{})
var key interface{}
var element interface{}
atoms = atoms[1:]
for {
if len(atoms) == 0 {
panic("Missing map end terminal")
}
if atoms[0].Typ == walk.AtomTerminal && atoms[0].Terminal() == walk.MapEnd {
atoms = atoms[1:]
break
}
key, atoms = assembleValue(atoms)
element, atoms = assembleValue(atoms)
keyString, keyIsString := key.(string)
if !keyIsString {
panic("Key is not string")
}
obj[keyString] = element
}
return obj, atoms
default:
panic("Invalid terminal")
}
default:
panic("Invalid atom")
}
}
func outputValue(atoms []walk.Atom, writer *bufio.Writer) {
if len(atoms) == 0 {
return
}
value, atoms := assembleValue(atoms)
if len(atoms) != 0 {
panic("Tried to output more than one JSON value")
}
bytes, err := json.MarshalIndent(value, "\t", "\t")
if err != nil {
panic("Error marshalling json into bytes")
}
_, err = writer.Write(bytes)
if err != nil {
panic("Error writing value")
}
}
type writerState int
const (
writerStateStart writerState = iota
writerStateValue
)
func NewJSONArrayWriter(writer *bufio.Writer) *JSONArrayWriter {
return &JSONArrayWriter {
writer: writer,
state: writerStateStart,
}
}
type JSONArrayWriter struct {
writer *bufio.Writer
state writerState
}
func (out *JSONArrayWriter) Write(item walk.WalkItem) error {
switch out.state {
case writerStateStart:
_, err := out.writer.WriteString("[\n\t")
if err != nil {
panic("Error outputting [ at beginning of array")
}
outputValue(item.Value, out.writer)
out.state = writerStateValue
return nil
case writerStateValue:
_, err := out.writer.WriteString(",\n\t")
if err != nil {
panic("Error outputting comma at the end of a value")
}
outputValue(item.Value, out.writer)
return nil
default:
panic("Invalid writer state")
}
}
func (out *JSONArrayWriter) AssertDone() {
if out.state == writerStateStart {
out.writer.WriteString("[")
}
out.writer.WriteString("\n]")
out.writer.Flush()
}
|
