Move JSON serialising, deserialising and walking code into a separate package

1 files changed, 0 insertions, 293 deletions

diff --git a/main/json.go b/main/json.go
index 77c3733..06ab7d0 100644
--- a/main/json.go
+++ b/main/json.go
@@ -1,294 +1 @@
 package main
-
-import (
-	"io"
-	"encoding/json"
-	"fmt"
-)
-
-type WalkItemStream struct {
-	channel chan WalkItem
-	rewinds []WalkItem
-}
-
-func (stream *WalkItemStream) next() (WalkItem, bool) {
-	if len(stream.rewinds) == 0 {
-		item, hasItem := <- stream.channel
-		return item, hasItem
-	}
-	item := stream.rewinds[len(stream.rewinds)-1]
-	stream.rewinds = stream.rewinds[0:len(stream.rewinds)-1]
-	return item, true
-}
-
-func (stream *WalkItemStream) rewind(item WalkItem) {
-	stream.rewinds = append(stream.rewinds, item)
-}
-
-func (stream *WalkItemStream) peek() (WalkItem, bool) {
-	item, hasItem := stream.next()
-	if !hasItem {
-		return item, false
-	}
-	stream.rewind(item)
-	return item, true
-}
-
-func tokenToValue(token json.Token) WalkValue {
-	switch token.(type) {
-		case nil:
-			return ValueNull {}
-		case bool:
-			return ValueBool(token.(bool))
-		case float64:
-			return ValueNumber(token.(float64))
-		case string:
-			return ValueString(token.(string))
-		default:
-			panic("Can't convert JSON token to value")
-	}
-}
-
-func readValue(dec *json.Decoder, path Path, out chan WalkItem) bool {
-	if !dec.More() {
-		return true
-	}
-	t, err := dec.Token()
-	if err == io.EOF {
-		return true
-	} else if err != nil {
-		panic("Invalid JSON")
-	}
-	switch t.(type) {
-		case nil, string, float64, bool:
-			v := tokenToValue(t)
-			out <- WalkItem {v, path}
-			return false
-		case json.Delim:
-			switch rune(t.(json.Delim)) {
-				case '[':
-					out <- WalkItem {ArrayBegin, path}
-					index := 0
-					for dec.More() {
-						empty := readValue(dec, append(path, index), out)
-						if empty {
-							break
-						}
-						index += 1
-					}
-					t, err := dec.Token()
-					if err != nil {
-						panic("Invalid JSON")
-					}
-					delim, isDelim := t.(json.Delim)
-					if !isDelim || delim != ']' {
-						panic("Expected ] in JSON")
-					}
-					out <- WalkItem{ArrayEnd, path}
-					return false
-				case '{':
-					out <- WalkItem {MapBegin, path}
-					for dec.More() {
-						t, _ := dec.Token()
-						key, keyIsString := t.(string)
-						if !keyIsString {
-							panic("Invalid JSON")
-						}
-						empty := readValue(dec, append(path, key), out)
-						if empty {
-							panic("Invalid JSON")
-						}
-					}
-					t, err := dec.Token()
-					if err != nil {
-						panic("Invalid JSON")
-					}
-					delim, isDelim := t.(json.Delim)
-					if !isDelim || delim != '}' {
-						panic("Expected } in JSON")
-					}
-					out <- WalkItem {MapEnd, path}
-					return false
-				default:
-					panic("Error parsing JSON")
-			}
-		default:
-			panic("Invalid JSON token")
-	}
-}
-
-func startWalk(dec *json.Decoder, out chan WalkItem) {
-	isEmpty := readValue(dec, nil, out)
-	if isEmpty {
-		panic("Missing JSON input")
-	}
-	close(out)
-}
-
-func Json(r io.Reader) chan WalkItem {
-	dec := json.NewDecoder(r)
-	out := make(chan WalkItem)
-	go startWalk(dec, out)
-	return out
-}
-
-func printIndent(indent int) {
-	for i := 0; i < indent; i += 1 {
-		fmt.Print("\t")
-	}
-}
-
-func jsonOutArray(in *WalkItemStream, indent int) {
-	fmt.Println("[")
-	token, hasToken := in.next()
-	if !hasToken {
-		panic("Missing ] in output JSON")
-	}
-	terminal, isTerminal := token.value.(TerminalValue)
-	if isTerminal && terminal == ArrayEnd {
-		fmt.Print("\n")
-		printIndent(indent)
-		fmt.Print("]")
-		return
-	}
-	in.rewind(token)
-	for {
-		valueToken := jsonOutValue(in, indent + 1, true)
-		if valueToken != nil {
-			panic("Missing value in output JSON array")
-		}
-		token, hasToken := in.next()
-		if !hasToken {
-			panic("Missing ] in output JSON")
-		}
-		terminal, isTerminal := token.value.(TerminalValue)
-		if isTerminal && terminal == ArrayEnd {
-			fmt.Print("\n")
-			printIndent(indent)
-			fmt.Print("]")
-			return
-		}
-		in.rewind(token)
-		fmt.Println(",")
-	}
-}
-
-func jsonOutMap(in *WalkItemStream, indent int) {
-	fmt.Println("{")
-	token, hasToken := in.next()
-	if !hasToken {
-		panic("Missing } in output JSON")
-	}
-	terminal, isTerminal := token.value.(TerminalValue)
-	if isTerminal && terminal == MapEnd {
-		fmt.Print("\n")
-		printIndent(indent)
-		fmt.Print("}")
-		return
-	}
-	in.rewind(token)
-	for {
-		keyToken, hasKeyToken := in.peek()
-		if !hasKeyToken {
-			panic("Missing map element")
-		}
-		printIndent(indent + 1)
-		if len(keyToken.path) == 0 {
-			panic("Map element missing key")
-		}
-		key := keyToken.path[len(keyToken.path)-1]
-		switch key.(type) {
-			case int:
-				fmt.Print(key.(int))
-			case string:
-				fmt.Printf("%q", key.(string))
-			default:
-				panic("Invalid path segment")
-		}
-		fmt.Print(": ")
-		valueToken := jsonOutValue(in, indent + 1, false)
-		if valueToken != nil {
-			panic("Missing value int output JSON map")
-		}
-		token, hasToken := in.next()
-		if !hasToken {
-			panic("Missing } in output JSON")
-		}
-		terminal, isTerminal := token.value.(TerminalValue)
-		if isTerminal && terminal == MapEnd {
-			fmt.Print("\n")
-			printIndent(indent)
-			fmt.Print("}")
-			return
-		}
-		in.rewind(token)
-		fmt.Println(",")
-	}
-}
-
-func jsonOutValue(in *WalkItemStream, indent int, doIndent bool) WalkValue {
-	token, hasToken := in.next()
-	if !hasToken {
-		panic("Missing JSON token in output")
-	}
-	switch token.value.(type) {
-		case ValueNull:
-			if doIndent {
-				printIndent(indent)
-			}
-			fmt.Printf("null")
-			return nil
-		case ValueBool:
-			if doIndent {
-				printIndent(indent)
-			}
-			if token.value.(ValueBool) {
-				fmt.Print("true")
-			} else {
-				fmt.Print("false")
-			}
-			return nil
-		case ValueNumber:
-			if doIndent {
-				printIndent(indent)
-			}
-			fmt.Printf("%v", token.value)
-			return nil
-		case ValueString:
-			if doIndent {
-				printIndent(indent)
-			}
-			fmt.Printf("%q", token.value)
-			return nil
-		case TerminalValue:
-			switch token.value.(TerminalValue) {
-				case ArrayBegin:
-					if doIndent {
-						printIndent(indent)
-					}
-					jsonOutArray(in, indent)
-					return nil
-				case MapBegin:
-					if doIndent {
-						printIndent(indent)
-					}
-					jsonOutMap(in, indent)
-					return nil
-				default:
-					return token
-			}
-		default:
-			panic("Invalid WalkValue")
-	}
-}
-
-func JsonOut(in chan WalkItem) {
-	stream := WalkItemStream {
-		channel: in,
-		rewinds: nil,
-	}
-	if jsonOutValue(&stream, 0, true) != nil {
-		panic("Invalid output JSON")
-	}
-	fmt.Print("\n")
-}