mirror of
https://github.com/scratchfoundation/scratch-vm.git
synced 2024-12-23 06:23:37 -05:00
Simplify execution by removing nextBlock
Everything is managed by the stack, including what the execute() function does.
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2cd6bf93bb
commit
526a260101
4 changed files with 70 additions and 57 deletions
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@ -6,40 +6,43 @@ var YieldTimers = require('../util/yieldtimers.js');
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*/
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*/
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var DEBUG_BLOCK_CALLS = true;
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var DEBUG_BLOCK_CALLS = true;
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var execute = function (sequencer, thread, blockId) {
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var execute = function (sequencer, thread) {
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var runtime = sequencer.runtime;
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var runtime = sequencer.runtime;
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// Current block to execute is the one on the top of the stack.
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var currentBlockId = thread.peekStack();
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var currentStackFrame = thread.peekStackFrame();
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// Save the yield timer ID, in case a primitive makes a new one
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// Save the yield timer ID, in case a primitive makes a new one
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// @todo hack - perhaps patch this to allow more than one timer per
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// @todo hack - perhaps patch this to allow more than one timer per
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// primitive, for example...
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// primitive, for example...
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var oldYieldTimerId = YieldTimers.timerId;
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var oldYieldTimerId = YieldTimers.timerId;
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var opcode = runtime.blocks.getOpcode(blockId);
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var opcode = runtime.blocks.getOpcode(currentBlockId);
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// Push the current block to the stack
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thread.pushStack(blockId);
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var currentStackFrame = thread.getLastStackFrame();
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// Generate values for arguments (inputs).
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// Generate values for arguments (inputs).
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var argValues = {};
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var argValues = {};
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// Add all fields on this block to the argValues.
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// Add all fields on this block to the argValues.
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var fields = runtime.blocks.getFields(blockId);
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var fields = runtime.blocks.getFields(currentBlockId);
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for (var fieldName in fields) {
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for (var fieldName in fields) {
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argValues[fieldName] = fields[fieldName].value;
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argValues[fieldName] = fields[fieldName].value;
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}
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}
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// Recursively evaluate input blocks.
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// Recursively evaluate input blocks.
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var inputs = runtime.blocks.getInputs(blockId);
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var inputs = runtime.blocks.getInputs(currentBlockId);
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for (var inputName in inputs) {
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for (var inputName in inputs) {
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var input = inputs[inputName];
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var input = inputs[inputName];
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var inputBlockId = input.block;
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var inputBlockId = input.block;
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var result = execute(sequencer, thread, inputBlockId);
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// Push to the stack to evaluate this input.
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thread.pushStack(inputBlockId);
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var result = execute(sequencer, thread);
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thread.popStack();
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argValues[input.name] = result;
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argValues[input.name] = result;
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}
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}
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if (!opcode) {
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if (!opcode) {
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console.warn('Could not get opcode for block: ' + blockId);
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console.warn('Could not get opcode for block: ' + currentBlockId);
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console.groupEnd();
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console.groupEnd();
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return;
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return;
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}
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}
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@ -62,12 +65,12 @@ var execute = function (sequencer, thread, blockId) {
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primitiveReturnValue = blockFunction(argValues, {
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primitiveReturnValue = blockFunction(argValues, {
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yield: thread.yield.bind(thread),
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yield: thread.yield.bind(thread),
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done: function() {
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done: function() {
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sequencer.proceedThread(thread, blockId);
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sequencer.proceedThread(thread);
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},
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},
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timeout: YieldTimers.timeout,
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timeout: YieldTimers.timeout,
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stackFrame: currentStackFrame,
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stackFrame: currentStackFrame,
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startSubstack: function () {
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startSubstack: function () {
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sequencer.stepToSubstack(thread, blockId);
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sequencer.stepToSubstack(thread);
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}
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}
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});
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});
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}
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}
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@ -86,8 +89,6 @@ var execute = function (sequencer, thread, blockId) {
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console.log('returned: ', primitiveReturnValue);
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console.log('returned: ', primitiveReturnValue);
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console.groupEnd();
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console.groupEnd();
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}
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}
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// Pop the stack and stack frame
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thread.popStack();
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return primitiveReturnValue;
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return primitiveReturnValue;
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}
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}
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};
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};
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@ -122,6 +122,7 @@ Runtime.prototype.getOpcodeFunction = function (opcode) {
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Runtime.prototype._pushThread = function (id) {
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Runtime.prototype._pushThread = function (id) {
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this.emit(Runtime.STACK_GLOW_ON, id);
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this.emit(Runtime.STACK_GLOW_ON, id);
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var thread = new Thread(id);
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var thread = new Thread(id);
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thread.pushStack(id);
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this.threads.push(thread);
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this.threads.push(thread);
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};
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};
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@ -49,17 +49,18 @@ Sequencer.prototype.stepThreads = function (threads) {
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var activeThread = threads[i];
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var activeThread = threads[i];
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if (activeThread.status === Thread.STATUS_RUNNING) {
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if (activeThread.status === Thread.STATUS_RUNNING) {
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// Normal-mode thread: step.
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// Normal-mode thread: step.
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this.stepThread(activeThread);
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this.startThread(activeThread);
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} else if (activeThread.status === Thread.STATUS_YIELD) {
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} else if (activeThread.status === Thread.STATUS_YIELD) {
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// Yield-mode thread: check if the time has passed.
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// Yield-mode thread: check if the time has passed.
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YieldTimers.resolve(activeThread.yieldTimerId);
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if (!YieldTimers.resolve(activeThread.yieldTimerId)) {
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numYieldingThreads++;
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numYieldingThreads++;
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}
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} else if (activeThread.status === Thread.STATUS_DONE) {
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} else if (activeThread.status === Thread.STATUS_DONE) {
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// Moved to a done state - finish up
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// Moved to a done state - finish up
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activeThread.status = Thread.STATUS_RUNNING;
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activeThread.status = Thread.STATUS_RUNNING;
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// @todo Deal with the return value
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// @todo Deal with the return value
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}
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}
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if (activeThread.nextBlock === null &&
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if (activeThread.stack.length === 0 &&
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activeThread.status === Thread.STATUS_DONE) {
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activeThread.status === Thread.STATUS_DONE) {
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// Finished with this thread - tell runtime to clean it up.
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// Finished with this thread - tell runtime to clean it up.
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inactiveThreads.push(activeThread);
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inactiveThreads.push(activeThread);
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@ -78,21 +79,27 @@ Sequencer.prototype.stepThreads = function (threads) {
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* Step the requested thread
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* Step the requested thread
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* @param {!Thread} thread Thread object to step
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* @param {!Thread} thread Thread object to step
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*/
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*/
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Sequencer.prototype.stepThread = function (thread) {
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Sequencer.prototype.startThread = function (thread) {
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// Save the current block and set the nextBlock.
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var currentBlockId = thread.peekStack();
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// If the primitive would like to do control flow,
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// it can overwrite nextBlock.
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var currentBlockId = thread.nextBlock;
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if (!currentBlockId || !this.runtime.blocks.getBlock(currentBlockId)) {
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if (!currentBlockId || !this.runtime.blocks.getBlock(currentBlockId)) {
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thread.status = Thread.STATUS_DONE;
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thread.status = Thread.STATUS_DONE;
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return;
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return;
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}
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}
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// Start showing run feedback in the editor.
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// Start showing run feedback in the editor.
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this.runtime.glowBlock(currentBlockId, true);
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this.runtime.glowBlock(currentBlockId, true);
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// Execute the block
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execute(this, thread, currentBlockId, false);
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// Push the current block to the stack, if executing for the first time.
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// If the block executed without yielding, move to done.
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if (thread.peekStack() != currentBlockId) {
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if (thread.status === Thread.STATUS_RUNNING && !thread.switchedStack) {
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thread.pushStack(currentBlockId);
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}
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// Execute the current block
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execute(this, thread);
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// If the block executed without yielding and without doing control flow,
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// move to done.
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if (thread.status === Thread.STATUS_RUNNING &&
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thread.peekStack() === currentBlockId) {
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this.proceedThread(thread, currentBlockId);
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this.proceedThread(thread, currentBlockId);
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}
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}
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};
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};
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@ -102,15 +109,16 @@ Sequencer.prototype.stepThread = function (thread) {
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* @param {!Thread} thread Thread object to step to substack.
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* @param {!Thread} thread Thread object to step to substack.
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* @param {string} currentBlockId Block which owns a substack to step to.
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* @param {string} currentBlockId Block which owns a substack to step to.
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*/
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*/
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Sequencer.prototype.stepToSubstack = function (thread, currentBlockId) {
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Sequencer.prototype.stepToSubstack = function (thread) {
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// Set nextBlock to the start of the substack
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var currentBlockId = thread.peekStack();
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var substack = this.runtime.blocks.getSubstack(currentBlockId);
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var substackId = this.runtime.blocks.getSubstack(currentBlockId);
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if (substack && substack.value) {
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if (substackId) {
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thread.nextBlock = substack.value;
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// Push substack ID to the thread's stack.
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thread.pushStack(substackId);
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} else {
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} else {
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thread.nextBlock = null;
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// Push null, so we come back to the current block.
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thread.pushStack(null);
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}
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}
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thread.switchedStack = true;
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};
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};
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/**
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/**
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@ -118,17 +126,21 @@ Sequencer.prototype.stepToSubstack = function (thread, currentBlockId) {
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* @param {!Thread} thread Thread object to proceed.
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* @param {!Thread} thread Thread object to proceed.
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* @param {string} currentBlockId Block we are finished with.
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* @param {string} currentBlockId Block we are finished with.
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*/
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*/
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Sequencer.prototype.proceedThread = function (thread, currentBlockId) {
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Sequencer.prototype.proceedThread = function (thread) {
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// Stop showing run feedback in the editor.
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var currentBlockId = thread.peekStack();
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// Mark the status as done and proceed to the next block.
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this.runtime.glowBlock(currentBlockId, false);
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this.runtime.glowBlock(currentBlockId, false);
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// Mark the thread as done and proceed to the next block.
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thread.status = Thread.STATUS_DONE;
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thread.status = Thread.STATUS_DONE;
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// Refresh nextBlock in case it has changed during a yield.
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// Pop from the stack - finished this level of execution.
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thread.nextBlock = this.runtime.blocks.getNextBlock(currentBlockId);
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thread.popStack();
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// If none is available, attempt to pop from the stack.
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// Push next connected block, if there is one.
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// First attempt to pop from the stack
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var nextBlockId = this.runtime.blocks.getNextBlock(currentBlockId);
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if (!thread.nextBlock && thread.stack.length > 0) {
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if (nextBlockId) {
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thread.nextBlock = thread.popStack();
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thread.pushStack(nextBlockId);
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}
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// Pop from the stack until we have a next block.
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while (thread.peekStack() === null && thread.stack.length > 0) {
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thread.popStack();
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}
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}
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};
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};
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@ -9,11 +9,7 @@ function Thread (firstBlock) {
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* @type {!string}
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* @type {!string}
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*/
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*/
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this.topBlock = firstBlock;
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this.topBlock = firstBlock;
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/**
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* ID of next block that the thread will execute, or null if none.
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* @type {?string}
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*/
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this.nextBlock = firstBlock;
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/**
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/**
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* Stack for the thread. When the sequencer enters a control structure,
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* Stack for the thread. When the sequencer enters a control structure,
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* the block is pushed onto the stack so we know where to exit.
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* the block is pushed onto the stack so we know where to exit.
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@ -38,12 +34,6 @@ function Thread (firstBlock) {
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* @type {number}
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* @type {number}
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*/
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*/
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this.yieldTimerId = -1;
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this.yieldTimerId = -1;
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/**
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* Whether the thread has switched stack in the course of execution.
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* @type {boolean}
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*/
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this.switchedStack = false;
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}
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}
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/**
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/**
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@ -83,7 +73,7 @@ Thread.prototype.pushStack = function (blockId) {
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/**
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/**
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* Pop last block on the stack and its stack frame.
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* Pop last block on the stack and its stack frame.
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* @returns {string} Block ID popped from the stack.
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* @return {string} Block ID popped from the stack.
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*/
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*/
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Thread.prototype.popStack = function () {
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Thread.prototype.popStack = function () {
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this.stackFrames.pop();
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this.stackFrames.pop();
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@ -91,10 +81,19 @@ Thread.prototype.popStack = function () {
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};
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};
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/**
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/**
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* Get last stack frame.
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* Get top stack item.
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* @return {?string} Block ID on top of stack.
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*/
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Thread.prototype.peekStack = function () {
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return this.stack[this.stack.length - 1];
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};
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/**
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* Get top stack frame.
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* @return {?Object} Last stack frame stored on this thread.
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* @return {?Object} Last stack frame stored on this thread.
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*/
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*/
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Thread.prototype.getLastStackFrame = function () {
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Thread.prototype.peekStackFrame = function () {
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return this.stackFrames[this.stackFrames.length - 1];
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return this.stackFrames[this.stackFrames.length - 1];
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};
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};
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