com.oracle.js.parser.ir.LexicalContext Maven / Gradle / Ivy
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package com.oracle.js.parser.ir;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import com.oracle.js.parser.Source;
/**
* A class that tracks the current lexical context of node visitation as a stack of {@link Block}
* 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.
*/
public class LexicalContext {
private LexicalContextNode[] stack;
private int sp;
/**
* Creates a new empty lexical context.
*/
public LexicalContext() {
this.stack = new LexicalContextNode[16];
}
/**
* Creates a copy of a lexical context.
*/
private LexicalContext(LexicalContext from) {
this.stack = Arrays.copyOf(from.stack, from.stack.length);
this.sp = from.sp;
}
/**
* @return all nodes in the LexicalContext.
*/
public Iterator getAllNodes() {
return new NodeIterator<>(LexicalContextNode.class);
}
/**
* Pushes a new block on top of the context, making it the innermost open block.
*
* @param the type of the new node
* @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 LexicalContextNode[] newStack = new LexicalContextNode[sp * 2];
System.arraycopy(stack, 0, newStack, 0, sp);
stack = newStack;
}
stack[sp] = node;
sp++;
return node;
}
/**
* Is the context empty?
*
* @return {@code true} if empty
*/
public boolean isEmpty() {
return sp == 0;
}
/**
* Pops the innermost block off the context and all nodes that has been contributed since it was
* put there.
*
* @param the type of the node to be popped
* @param node the node expected to be popped, used to detect unbalanced pushes/pops
*
* @return the node that was popped
*/
@SuppressWarnings("unchecked")
public T pop(final T node) {
--sp;
final LexicalContextNode popped = stack[sp];
stack[sp] = null;
return (T) popped;
}
/**
* Check if a node is in the lexical context.
*
* @param node node to check for
*
* @return {@code true} if in the context
*/
public boolean contains(final LexicalContextNode node) {
for (int i = 0; i < sp; i++) {
if (stack[i] == node) {
return true;
}
}
return false;
}
/**
* Replace a node on the lexical context with a new one. Normally you should try to engineer IR
* traversals so this isn't needed
*
* @param oldNode old node
* @param newNode new node
*
* @return the new node
*/
public LexicalContextNode replace(final LexicalContextNode oldNode, final LexicalContextNode newNode) {
for (int i = sp - 1; i >= 0; i--) {
if (stack[i] == oldNode) {
assert i == sp - 1 : "violation of contract - we always expect to find the replacement node on top of the lexical context stack: " + newNode + " has " + stack[i + 1].getClass() +
" above it";
stack[i] = newNode;
break;
}
}
return newNode;
}
/**
* 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<>(Block.class);
}
/**
* 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<>(FunctionNode.class);
}
/**
* @return the innermost block in the context.
*/
public Block getCurrentBlock() {
return getBlocks().next();
}
/**
* @return the innermost function in the context.
*/
public FunctionNode getCurrentFunction() {
for (int i = sp - 1; i >= 0; i--) {
if (stack[i] instanceof FunctionNode) {
return (FunctionNode) stack[i];
}
}
return null;
}
public FunctionNode getCurrentNonArrowFunction() {
final Iterator iter = getFunctions();
while (iter.hasNext()) {
final FunctionNode fn = iter.next();
if (!fn.isArrow()) {
return fn;
}
}
return null;
}
/**
* Returns the innermost scope in the context.
*/
public Scope getCurrentScope() {
NodeIterator iterator = new NodeIterator<>(LexicalContextScope.class);
return iterator.hasNext() ? iterator.next().getScope() : null;
}
/**
* @return the innermost class in the context.
*/
public ClassNode getCurrentClass() {
NodeIterator iterator = new NodeIterator<>(ClassNode.class);
return iterator.hasNext() ? iterator.next() : null;
}
public boolean inModule() {
for (Iterator functions = getFunctions(); functions.hasNext();) {
FunctionNode function = functions.next();
if (function.isModule()) {
return true;
}
}
return false;
}
public LexicalContext copy() {
return new LexicalContext(this);
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append("[ ");
for (int i = 0; i < sp; i++) {
final Object node = stack[i];
sb.append(node.getClass().getSimpleName());
sb.append('@');
sb.append(id(node));
sb.append(':');
if (node instanceof FunctionNode) {
final FunctionNode fn = (FunctionNode) node;
final Source source = fn.getSource();
String src = source.toString();
int indexSep = src.lastIndexOf(':');
if (indexSep >= 0) {
src = src.substring(indexSep);
}
sb.append(src);
sb.append(' ');
sb.append(fn.getLineNumber());
}
sb.append(' ');
}
sb.append(" ==> ]");
return sb.toString();
}
private static String id(Object x) {
return String.format("0x%08x", System.identityHashCode(x));
}
private class NodeIterator implements Iterator {
private int index;
private T next;
private final Class clazz;
private LexicalContextNode until;
NodeIterator(final Class clazz) {
this(clazz, null);
}
NodeIterator(final Class clazz, final LexicalContextNode 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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