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Refactor parser state into separate class

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This commit is contained in:
Vladimir Grichina 2019-01-07 23:26:05 -08:00
parent b036c86f5f
commit f3800cc7d7
1 changed files with 33 additions and 24 deletions
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57
assembly/decoder.ts
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@ -75,33 +75,42 @@ let CHAR_9 = "9".charCodeAt(0);
let CHAR_A = "A".charCodeAt(0); let CHAR_A = "A".charCodeAt(0);
let CHAR_A_LOWER = "a".charCodeAt(0); let CHAR_A_LOWER = "a".charCodeAt(0);
export class JSONDecoder<JSONHandlerT extends JSONHandler> { export class DecoderState {
handler: JSONHandlerT;
readIndex: i32 = 0; readIndex: i32 = 0;
buffer: Uint8Array = null; buffer: Uint8Array = null;
lastKey: string = null; lastKey: string = null;
}
export class JSONDecoder<JSONHandlerT extends JSONHandler> {
handler: JSONHandlerT;
state: DecoderState;
constructor(handler: JSONHandlerT) { constructor(handler: JSONHandlerT) {
this.handler = handler; this.handler = handler;
} }
deserialize(buffer: Uint8Array, startIndex: i32 = 0): void { deserialize(buffer: Uint8Array, decoderState: DecoderState = null): void {
this.readIndex = startIndex; if (decoderState) {
this.buffer = buffer; this.state = decoderState;
this.lastKey = null } else {
this.state = new DecoderState();
this.state.readIndex = 0;
this.state.buffer = buffer;
this.state.lastKey = null;
}
assert(this.parseValue(), "Cannot parse JSON"); assert(this.parseValue(), "Cannot parse JSON");
// TODO: Error if input left // TODO: Error if input left
} }
private peekChar(): i32 { private peekChar(): i32 {
return this.buffer[this.readIndex]; return this.state.buffer[this.state.readIndex];
} }
private readChar(): i32 { private readChar(): i32 {
assert(this.readIndex < this.buffer.length, "Unexpected input end"); assert(this.state.readIndex < this.state.buffer.length, "Unexpected input end");
return this.buffer[this.readIndex++]; return this.state.buffer[this.state.readIndex++];
} }
private parseValue(): bool { private parseValue(): bool {
@ -120,7 +129,7 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
if (this.peekChar() != "{".charCodeAt(0)) { if (this.peekChar() != "{".charCodeAt(0)) {
return false; return false;
} }
if (this.handler.pushObject(this.lastKey)) { if (this.handler.pushObject(this.state.lastKey)) {
this.readChar(); this.readChar();
this.skipWhitespace(); this.skipWhitespace();
@ -142,7 +151,7 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
private parseKey(): void { private parseKey(): void {
this.skipWhitespace(); this.skipWhitespace();
this.lastKey = this.readString(); this.state.lastKey = this.readString();
this.skipWhitespace(); this.skipWhitespace();
assert(this.readChar() == ":".charCodeAt(0), "Expected ':'"); assert(this.readChar() == ":".charCodeAt(0), "Expected ':'");
} }
@ -151,8 +160,8 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
if (this.peekChar() != "[".charCodeAt(0)) { if (this.peekChar() != "[".charCodeAt(0)) {
return false; return false;
} }
if (this.handler.pushArray(this.lastKey)) { if (this.handler.pushArray(this.state.lastKey)) {
this.lastKey = null; this.state.lastKey = null;
this.readChar(); this.readChar();
this.skipWhitespace(); this.skipWhitespace();
@ -175,13 +184,13 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
if (this.peekChar() != '"'.charCodeAt(0)) { if (this.peekChar() != '"'.charCodeAt(0)) {
return false; return false;
} }
this.handler.setString(this.lastKey, this.readString()); this.handler.setString(this.state.lastKey, this.readString());
return true; return true;
} }
private readString(): string { private readString(): string {
assert(this.readChar() == '"'.charCodeAt(0), "Expected double-quoted string"); assert(this.readChar() == '"'.charCodeAt(0), "Expected double-quoted string");
let savedIndex = this.readIndex; let savedIndex = this.state.readIndex;
let stringParts: Array<string> = new Array<string>(); let stringParts: Array<string> = new Array<string>();
for (;;) { for (;;) {
let byte = this.readChar(); let byte = this.readChar();
@ -189,16 +198,16 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
// TODO: Make sure unicode handled properly // TODO: Make sure unicode handled properly
if (byte == '"'.charCodeAt(0)) { if (byte == '"'.charCodeAt(0)) {
stringParts.push( stringParts.push(
String.fromUTF8(this.buffer.buffer.data + savedIndex, this.readIndex - savedIndex - 1)); String.fromUTF8(this.state.buffer.buffer.data + savedIndex, this.state.readIndex - savedIndex - 1));
return stringParts.join(""); return stringParts.join("");
} }
if (byte == "\\".charCodeAt(0)) { if (byte == "\\".charCodeAt(0)) {
if (this.readIndex > savedIndex + 1) { if (this.state.readIndex > savedIndex + 1) {
stringParts.push( stringParts.push(
String.fromUTF8(this.buffer.buffer.data + savedIndex, this.readIndex - savedIndex - 1)); String.fromUTF8(this.state.buffer.buffer.data + savedIndex, this.state.readIndex - savedIndex - 1));
} }
stringParts.push(this.readEscapedChar()); stringParts.push(this.readEscapedChar());
savedIndex = this.readIndex; savedIndex = this.state.readIndex;
} }
} }
// Should never happen // Should never happen
@ -271,7 +280,7 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
digits++; digits++;
} }
if (digits > 0) { if (digits > 0) {
this.handler.setInteger(this.lastKey, number * sign); this.handler.setInteger(this.state.lastKey, number * sign);
return true; return true;
} }
return false; return false;
@ -280,12 +289,12 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
private parseBoolean(): bool { private parseBoolean(): bool {
if (this.peekChar() == FALSE_STR.charCodeAt(0)) { if (this.peekChar() == FALSE_STR.charCodeAt(0)) {
this.readAndAssert(FALSE_STR); this.readAndAssert(FALSE_STR);
this.handler.setBoolean(this.lastKey, false); this.handler.setBoolean(this.state.lastKey, false);
return true; return true;
} }
if (this.peekChar() == TRUE_STR.charCodeAt(0)) { if (this.peekChar() == TRUE_STR.charCodeAt(0)) {
this.readAndAssert(TRUE_STR); this.readAndAssert(TRUE_STR);
this.handler.setBoolean(this.lastKey, true); this.handler.setBoolean(this.state.lastKey, true);
return true; return true;
} }
@ -295,7 +304,7 @@ export class JSONDecoder<JSONHandlerT extends JSONHandler> {
private parseNull(): bool { private parseNull(): bool {
if (this.peekChar() == NULL_STR.charCodeAt(0)) { if (this.peekChar() == NULL_STR.charCodeAt(0)) {
this.readAndAssert(NULL_STR); this.readAndAssert(NULL_STR);
this.handler.setNull(this.lastKey); this.handler.setNull(this.state.lastKey);
return true; return true;
} }
return false; return false;