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* The Universal Permissive License (UPL), Version 1.0
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package com.oracle.js.parser;
import java.util.Iterator;
import java.util.NoSuchElementException;
import com.oracle.js.parser.ir.Statement;
/**
* A class that tracks the current lexical context of node visitation as a stack of
* {@code ParserContextNode} nodes. Has special methods to retrieve useful subsets of the context.
*
* This is implemented with a primitive array and a stack pointer, because it really makes a
* difference performance wise. None of the collection classes were optimal
*/
class ParserContext {
private ParserContextNode[] stack;
private int sp;
private static final int INITIAL_DEPTH = 16;
/**
* Constructs a ParserContext, initializes the stack
*/
ParserContext() {
this.sp = 0;
this.stack = new ParserContextNode[INITIAL_DEPTH];
}
/**
* Pushes a new block on top of the context, making it the innermost open block.
*
* @param node the new node
* @return The node that was pushed
*/
public T push(final T node) {
assert !contains(node);
if (sp == stack.length) {
final ParserContextNode[] newStack = new ParserContextNode[sp * 2];
System.arraycopy(stack, 0, newStack, 0, sp);
stack = newStack;
}
stack[sp] = node;
sp++;
return node;
}
/**
* The topmost node on the stack
*
* @return The topmost node on the stack
*/
public ParserContextNode peek() {
return stack[sp - 1];
}
/**
* Removes and returns the topmost Node from the stack.
*
* @param node The node expected to be popped, used for sanity check
* @return The removed node
*/
public T pop(final T node) {
--sp;
@SuppressWarnings("unchecked")
final T popped = (T) stack[sp];
stack[sp] = null;
assert node == popped;
return popped;
}
/**
* Tests if a node is on the stack.
*
* @param node The node to test
* @return true if stack contains node, false otherwise
*/
public boolean contains(final ParserContextNode node) {
for (int i = 0; i < sp; i++) {
if (stack[i] == node) {
return true;
}
}
return false;
}
/**
* Returns the topmost {@link ParserContextBreakableNode} on the stack, null if none on stack
*
* @return Returns the topmost {@link ParserContextBreakableNode} on the stack, null if none on
* stack
*/
private ParserContextBreakableNode getBreakable() {
for (final NodeIterator iter = new NodeIterator<>(ParserContextBreakableNode.class, getCurrentFunction()); iter.hasNext();) {
final ParserContextBreakableNode next = iter.next();
if (next.isBreakableWithoutLabel()) {
return next;
}
}
return null;
}
/**
* Find the breakable node corresponding to this label.
*
* @param labelName name of the label to search for. If null, the closest breakable node will be
* returned unconditionally, e.g. a while loop with no label
* @return closest breakable node
*/
public ParserContextBreakableNode getBreakable(final String labelName) {
if (labelName != null) {
final ParserContextLabelNode foundLabel = findLabel(labelName);
if (foundLabel != null) {
// iterate to the nearest breakable to the foundLabel
ParserContextBreakableNode breakable = null;
for (final NodeIterator iter = new NodeIterator<>(ParserContextBreakableNode.class, foundLabel); iter.hasNext();) {
breakable = iter.next();
}
return breakable;
}
return null;
} else {
return getBreakable();
}
}
/**
* Returns the loop node of the current loop, or null if not inside a loop
*
* @return loop noder
*/
public ParserContextLoopNode getCurrentLoop() {
final Iterator iter = new NodeIterator<>(ParserContextLoopNode.class, getCurrentFunction());
return iter.hasNext() ? iter.next() : null;
}
private ParserContextLoopNode getContinueTo() {
return getCurrentLoop();
}
/**
* Find the continue target node corresponding to this label.
*
* @param labelName label name to search for. If null the closest loop node will be returned
* unconditionally, e.g. a while loop with no label
* @return closest continue target node
*/
public ParserContextLoopNode getContinueTo(final String labelName) {
if (labelName != null) {
final ParserContextLabelNode foundLabel = findLabel(labelName);
if (foundLabel != null) {
// iterate to the nearest loop to the foundLabel
ParserContextLoopNode loop = null;
for (final NodeIterator iter = new NodeIterator<>(ParserContextLoopNode.class, foundLabel); iter.hasNext();) {
loop = iter.next();
}
return loop;
}
return null;
}
return getContinueTo();
}
/**
* Get the function body of a function node on the stack. This will trigger an assertion if node
* isn't present
*
* @param functionNode function node
* @return body of function node
*/
public ParserContextBaseNode getFunctionBody(final ParserContextFunctionNode functionNode) {
for (int i = sp - 1; i >= 0; i--) {
if (stack[i] == functionNode) {
return (ParserContextBaseNode) stack[i + 1];
}
}
throw new AssertionError(functionNode.getName() + " not on context stack");
}
/**
* Check the stack for a given label node by name
*
* @param name name of the label
* @return LabelNode if found, null otherwise
*/
public ParserContextLabelNode findLabel(final String name) {
for (final Iterator iter = new NodeIterator<>(ParserContextLabelNode.class, getCurrentFunction()); iter.hasNext();) {
final ParserContextLabelNode next = iter.next();
if (next.getLabelName().equals(name)) {
return next;
}
}
return null;
}
/**
* Prepends a statement to the current node.
*
* @param statement The statement to prepend
*/
public void prependStatementToCurrentNode(final Statement statement) {
assert statement != null;
stack[sp - 1].prependStatement(statement);
}
/**
* Appends a statement to the current Node.
*
* @param statement The statement to append
*/
public void appendStatementToCurrentNode(final Statement statement) {
assert statement != null;
stack[sp - 1].appendStatement(statement);
}
/**
* Returns the innermost function in the context.
*
* @return the innermost function in the context.
*/
public ParserContextFunctionNode getCurrentFunction() {
for (int i = sp - 1; i >= 0; i--) {
if (stack[i] instanceof ParserContextFunctionNode) {
return (ParserContextFunctionNode) stack[i];
}
}
return null;
}
/**
* Returns an iterator over all blocks in the context, with the top block (innermost lexical
* context) first.
*
* @return an iterator over all blocks in the context.
*/
public Iterator getBlocks() {
return new NodeIterator<>(ParserContextBlockNode.class);
}
/**
* Returns the innermost block in the context.
*
* @return the innermost block in the context.
*/
public ParserContextBlockNode getCurrentBlock() {
return getBlocks().next();
}
/**
* The last statement added to the context
*
* @return The last statement added to the context
*/
public Statement getLastStatement() {
if (sp == 0) {
return null;
}
final ParserContextNode top = stack[sp - 1];
final int s = top.getStatements().size();
return s == 0 ? null : top.getStatements().get(s - 1);
}
/**
* Returns an iterator over all functions in the context, with the top (innermost open) function
* first.
*
* @return an iterator over all functions in the context.
*/
public Iterator getFunctions() {
return new NodeIterator<>(ParserContextFunctionNode.class);
}
public ParserContextModuleNode getCurrentModule() {
final Iterator iter = new NodeIterator<>(ParserContextModuleNode.class, getCurrentFunction());
return iter.hasNext() ? iter.next() : null;
}
private class NodeIterator implements Iterator {
private int index;
private T next;
private final Class clazz;
private ParserContextNode until;
NodeIterator(final Class clazz) {
this(clazz, null);
}
NodeIterator(final Class clazz, final ParserContextNode until) {
this.index = sp - 1;
this.clazz = clazz;
this.until = until;
this.next = findNext();
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public T next() {
if (next == null) {
throw new NoSuchElementException();
}
final T lnext = next;
next = findNext();
return lnext;
}
@SuppressWarnings("unchecked")
private T findNext() {
for (int i = index; i >= 0; i--) {
final Object node = stack[i];
if (node == until) {
return null;
}
if (clazz.isAssignableFrom(node.getClass())) {
index = i - 1;
return (T) node;
}
}
return null;
}
}
}
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