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@@ -129,6 +129,15 @@ static void emitBytes(uint8_t byte1, uint8_t byte2) {
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emitByte(byte1);
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emitByte(byte2);
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}
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+static void emitLoop(int loopStart) {
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+ emitByte(OP_LOOP);
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+
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+ int offset = currentChunk()->count - loopStart + 2;
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+ if (offset > UINT16_MAX) error("Loop body too large.");
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+
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+ emitByte((offset >> 8) & 0xFF);
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+ emitByte(offset & 0xFF);
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+}
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static int emitJump(uint8_t instruction) {
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emitByte(instruction);
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emitByte(0xff);// 占位字节，后面填入需要跳转的 offset
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@@ -178,6 +187,71 @@ static void patchJump(int offset) {
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currentChunk()->code[offset] = (jump >> 8) & 0xFF;
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currentChunk()->code[offset + 1] = jump & 0xFF;
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}
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+static void forStatement() {
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+ /**
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+ * *********************************************************
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+ * initializer clause
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+ * L4: condition expression
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+ * OP_JUMP_IF_FALSE L1
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+ * OP_POP
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+ * OP_JUMP L3
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+ * L2: increment expression
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+ * OP_POP
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+ * OP_LOOP L4
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+ * L3: body statement
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+ * OP_LOOP L2
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+ * L1: OP_POP
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+ * continues...
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+ * *********************************************************
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+ */
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+ beginScope();
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+ // for(I;II;III)
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+ consume(TOKEN_LEFT_PAREN, "Expect '(' after 'for'.");
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+
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+ ///! I.<<Initializer Part>>
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+ if (match(TOKEN_SEMICOLON)) {
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+ // No initializer.
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+ } else if (match(TOKEN_VAR)) {
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+ varDeclaration();
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+ } else {
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+ expressionStatement();// ; op_pop
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+ }
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+
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+ ///! II.<<Condition Part>>
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+ int loopStart = currentChunk()->count;
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+ int exitJump = -1;
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+ if (!match(TOKEN_SEMICOLON)) {
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+ expression();
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+ consume(TOKEN_SEMICOLON, "Expect ';' after loop conditon. ");
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+
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+ // Jump out of the loop if the condition is false.
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+ exitJump = emitJump(OP_JUMP_IF_FALSE);
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+ emitByte(OP_POP);
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+ }
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+
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+ ///! III.<<Increment Clause>>
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+ if (!match(TOKEN_RIGHT_PAREN)) {
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+ int bodyJump = emitJump(OP_JUMP);
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+ int incrementStart = currentChunk()->count;
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+ expression();
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+ emitByte(OP_POP);
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+ consume(TOKEN_RIGHT_PAREN, "Expect ')' after for clauses.");
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+
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+ emitLoop(loopStart);
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+ loopStart = incrementStart;
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+ patchJump(bodyJump);
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+ }
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+
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+ ///! <<Body Part>>
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+ statement();
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+ emitLoop(loopStart);
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+
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+ if (exitJump != -1) {
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+ patchJump(exitJump);
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+ emitByte(OP_POP);// Condition.
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+ }
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+ endScope();
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+}
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static void ifStatement() {
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consume(TOKEN_LEFT_PAREN, "Expect '(' after 'if'.");
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expression();
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@@ -195,6 +269,21 @@ static void ifStatement() {
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if (match(TOKEN_ELSE)) statement();// else branch statement
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patchJump(elseJump);
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}
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+static void whileStatement() {
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+ int loopStart = currentChunk()->count;
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+ consume(TOKEN_LEFT_PAREN, "Expect '(' after 'while'.");
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+ expression();// while condition.
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+ consume(TOKEN_RIGHT_PAREN, "Expect ')' after condition.");
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+
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+ int exitJump = emitJump(OP_JUMP_IF_FALSE);
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+ emitByte(OP_POP);
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+
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+ statement();// while body.
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+ emitLoop(loopStart);
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+
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+ patchJump(exitJump);
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+ emitByte(OP_POP);
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+}
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static void printStatement() {
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expression();
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consume(TOKEN_SEMICOLON, "Expect ';' after value.");
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@@ -250,8 +339,12 @@ static void block() {
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static void statement() {
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if (match(TOKEN_PRINT)) {
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printStatement();
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+ } else if (match(TOKEN_FOR)) {
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+ forStatement();
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} else if (match(TOKEN_IF)) {
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ifStatement();
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+ } else if (match(TOKEN_WHILE)) {
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+ whileStatement();
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} else if (match(TOKEN_LEFT_BRACE)) {
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///! block → "{" declaration* "}" ;
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beginScope();
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@@ -303,6 +396,36 @@ static void string(__attribute__((unused)) bool canAssign) {
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emitConstant(OBJ_VAL(copyString(parser.previous.start + 1,
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parser.previous.length - 2)));
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}
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+static void and_(__attribute__((unused)) bool canAssign) {
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+ /// left operand expression
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+ /// OP_JUMP_IF_FALSE b
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+ /// OP_POP
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+ /// right operand expression
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+ /// b: continues...
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+ int endJump = emitJump(OP_JUMP_IF_FALSE);
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+
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+ emitByte(OP_POP);
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+
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+ parsePrecedence(PREC_AND);// right operand expression
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+
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+ patchJump(endJump);
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+}
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+static void or_(__attribute__((unused)) bool canAssign) {
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+ /// left operand expression
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+ /// OP_JUMP_IF_FALSE b1
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+ /// OP_JUMP b2
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+ /// b1: OP_POP
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+ /// right operand expression
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+ /// b2: continue
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+ int elseJump = emitJump(OP_JUMP_IF_FALSE);
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+ int endJump = emitJump(OP_JUMP);
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+
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+ patchJump(elseJump);
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+ emitByte(OP_POP);
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+
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+ parsePrecedence(PREC_OR);// right operand expression
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+ patchJump(endJump);
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+}
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static int resolveLocal(Compiler *compile, Token *name) {
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for (int i = compile->localCount - 1; i >= 0; i--) {
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Local *local = &compile->locals[i];
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@@ -433,7 +556,7 @@ ParseRule rules[] = {
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[TOKEN_IDENTIFIER] = {variable, NULL, PREC_NONE},
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[TOKEN_STRING] = {string, NULL, PREC_NONE},
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[TOKEN_NUMBER] = {number, NULL, PREC_NONE},
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- [TOKEN_AND] = {NULL, NULL, PREC_NONE},
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+ [TOKEN_AND] = {NULL, and_, PREC_AND},
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[TOKEN_CLASS] = {NULL, NULL, PREC_NONE},
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[TOKEN_ELSE] = {NULL, NULL, PREC_NONE},
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[TOKEN_FALSE] = {literal, NULL, PREC_NONE},
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@@ -441,7 +564,7 @@ ParseRule rules[] = {
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[TOKEN_FUN] = {NULL, NULL, PREC_NONE},
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[TOKEN_IF] = {NULL, NULL, PREC_NONE},
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[TOKEN_NIL] = {literal, NULL, PREC_NONE},
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- [TOKEN_OR] = {NULL, NULL, PREC_NONE},
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+ [TOKEN_OR] = {NULL, or_, PREC_OR},
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[TOKEN_PRINT] = {NULL, NULL, PREC_NONE},
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[TOKEN_RETURN] = {NULL, NULL, PREC_NONE},
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[TOKEN_SUPER] = {NULL, NULL, PREC_NONE},
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@@ -532,7 +655,6 @@ static void defineVariable(uint8_t global) {
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// 本地变量，直接退出
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return;
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}
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-
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emitBytes(OP_DEFINE_GLOBAL, global);
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}
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static ParseRule *getRule(TokenType type) {
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