public class GrammarAST {
/**
+ * Returns a Union representing the metagrammar (<tt>meta.g</tt>); the Tree produced by
+ * parsing with this Union should be provided to <tt>buildFromAST</tt>
+ */
+ public static Union getMetaGrammar() {
+ return buildFromAST(MetaGrammar.meta, "s", new File[0]);
+ }
+
+ /**
* Create a grammar from a parse tree and binding resolver
*
* @param t a tree produced by parsing a grammar using the metagrammar
if (head.equals("Elements")) return new Seq((ElementNode[])Reflection.rebuild(walkChildren(t), ElementNode[].class));
if (head.equals("NonTerminalReference")) return new ReferenceNode(stringifyChildren(t.child(0)));
if (head.equals(")")) return new ReferenceNode(stringifyChildren(t.child(0)), true);
- if (head.equals("{")) return new BracedNode(walkSeq(t.child(0)));
if (head.equals("::")) return walkSeq(t.child(1)).tag(walkString(t.child(0)));
if (head.equals("...")) return new DropNode(new RepeatNode(new TildeNode(new AtomNode()), null, true, true, false));
if (head.equals("!")) return new DropNode(walkElement(t.child(0)));
if (head.equals("^")) return new LiteralNode(walkString(t.child(0)), true);
- if (head.equals("`")) return walkElement(t.child(0)).lifted();
+ if (head.equals("`")) return new BacktickNode(walkElement(t.child(0)));
if (head.equals("Quoted")) return stringifyChildren(t);
if (head.equals("Literal")) return new LiteralNode(walkString(t.child(0)));
if (head.equals("->")) return walkSeq(t.child(0)).follow(walkElement(t.child(1)));
if (head.equals("DropNT")) return new NonTerminalNode(walkString(t.child(0)), (Seq[][])walkChildren(t.child(1)), false, null, true);
if (head.equals("=")) return new NonTerminalNode(walkString(t.child(0)), (Seq[][])walk(t.child(2)),
true, t.size()==2 ? null : walkString(t.child(1)), false);
- if (head.equals("&")) return and2(walkSeq(t.child(0)), walkSeq(t.child(1)));
- if (head.equals("&~")) return andnot2(walkSeq(t.child(0)), walkSeq(t.child(1)));
+ if (head.equals("&")) return walkSeq(t.child(0)).and(walkSeq(t.child(1)));
+ if (head.equals("&~")) return walkSeq(t.child(0)).andnot(walkSeq(t.child(1)));
if (head.equals("/")) return (walkSeq(t.child(0))).separate(walkElement(t.child(1)));
if (head.equals("()")) return new LiteralNode("");
if (head.equals("[")) return new AtomNode((char[][])Reflection.rebuild(walkChildren(t), char[][].class));
try {
String newPrefix = t.size()<2 ? "" : (walkString(t.child(1))+".");
FileInputStream fis = new FileInputStream(file);
- Tree tr = new CharParser(MetaGrammar.newInstance()).parse(fis).expand1();
+ Tree tr = new CharParser(getMetaGrammar()).parse(fis).expand1();
return (GrammarNode)new GrammarAST(includes, newPrefix).walk(tr);
} catch (Exception e) {
throw new RuntimeException("while parsing " + file, e);
}
}
+ /** a node in the AST which is resolved into an Element */
+ private abstract class ElementNode {
+ public boolean isLifted() { return false; }
+ public boolean drop(Context cx) { return false; }
+ public Atom toAtom(Context cx) { throw new Error("can't convert a " + this.getClass().getName() + " to an atom: " + this); }
+ public abstract Element build(Context cx, NonTerminalNode cnt, boolean dropall);
+ }
+
private class UnionNode extends ElementNode {
public Seq[][] sequences;
public String sep = null;
for(int i=0; i<elements.length; i++) {
if (elements[i]==null)
throw new RuntimeException();
- elements[i].ownerSeq = this;
}
// FIXME: this whole mechanism is sketchy
if (check)
}
public Seq tag(String tag) { this.tag = tag; return this; }
public Seq follow(ElementNode follow) { this.follow = follow; return this; }
- public Seq and(Seq s) { and.add(s); return this; }
- public Seq andnot(Seq s) { not.add(s); return this; }
+ public Seq and(Seq s) { and.add(s); s.alwaysDrop = true; return this; }
+ public Seq andnot(Seq s) { not.add(s); s.alwaysDrop = true; return this; }
public Seq separate(ElementNode sep) {
ElementNode[] elements = new ElementNode[this.elements.length * 2 - 1];
for(int i=0; i<this.elements.length; i++) {
for(int i=0; i<elements.length; i++) {
if (dropall) drops[i] = true;
else drops[i] = elements[i].drop(cx);
- if (elements[i].getOwnerTag() != null)
- tag = elements[i].getOwnerTag();
+ if (elements[i] instanceof LiteralNode && ((LiteralNode)elements[i]).caret) {
+ if (tag != null) throw new RuntimeException("cannot have multiple tags in a sequence: " + this);
+ tag = ((LiteralNode)elements[i]).getLiteralTag();
+ }
}
Sequence ret = null;
int idx = -1;
throw new RuntimeException("multiple non-dropped elements in sequence: " + Sequence.create("", els));
boolean[] lifts = new boolean[elements.length];
for(int i=0; i<elements.length; i++)
- lifts[i] = elements[i].lifted;
+ lifts[i] = elements[i].isLifted();
if (!multiNonDrop) {
if (idx == -1)
ret = tag==null
}
public boolean drop(Context cx) { return resolve(cx).drop(cx); }
public Element build(Context cx, NonTerminalNode cnt, boolean dropall) {
- /*
- if (!this.nonTerminal.startsWith(prefix))
- nonTerminal = prefix + nonTerminal;
- */
Element ret = cx.get(nonTerminal);
if (ret == null) throw new RuntimeException("unknown nonterminal \""+nonTerminal+"\"");
return ret;
this.string = string;
this.caret = caret;
}
- public String getOwnerTag() { return caret ? thePrefix+string : super.getOwnerTag(); }
+ public String getLiteralTag() { return caret ? thePrefix+string : null; }
public String toString() { return "\""+string+"\""; }
public boolean drop(Context cx) { return true; }
public Atom toAtom(Context cx) {
}
}
- private abstract class ElementNode {
- public boolean lifted = false;
- public Seq ownerSeq = null;
- public String getOwnerTag() { return null; }
- public ElementNode lifted() { this.lifted = true; return this; }
- public boolean drop(Context cx) { return false; }
- public Atom toAtom(Context cx) { throw new Error("can't convert a " + this.getClass().getName() + " to an atom: " + this); }
- public abstract Element build(Context cx, NonTerminalNode cnt, boolean dropall);
- }
-
private abstract class ElementNodeWrapper extends ElementNode {
protected ElementNode _e;
public ElementNodeWrapper(ElementNode e) { this._e = e; }
- public String getOwnerTag() { return _e.getOwnerTag(); }
public boolean drop(Context cx) { return _e.drop(cx); }
public Atom toAtom(Context cx) { return _e.toAtom(cx); }
public Element build(Context cx, NonTerminalNode cnt, boolean dropall) { return _e.build(cx, cnt, dropall); }
}
+ private class BacktickNode extends ElementNodeWrapper {
+ public BacktickNode(ElementNode e) { super(e); }
+ public boolean isLifted() { return true; }
+ }
+
private class TildeNode extends ElementNodeWrapper {
public TildeNode(ElementNode e) { super(e); }
public Atom toAtom(Context cx) { return (Atom)((Topology<Character>)_e.toAtom(cx).complement()); }
public boolean drop(Context cx) { return true; }
}
- // FIXME: doesn't this require a tag?
- private class BracedNode extends ElementNode {
- public Seq body;
- public BracedNode(Seq seq) { this.body = seq; }
- public Element build(Context cx, NonTerminalNode cnt, boolean dropall) {
- Union u = new Union(null, false);
- Sequence s = body.build(cx, u, null, dropall);
- Union u2 = new Union(null, false);
- u2.add(Sequence.create(new Element[] {
- CharAtom.leftBrace,
- u,
- CharAtom.rightBrace
- }, 1));
- return u2;
- }
- }
-
- public Seq and2(Seq s, Seq a) { a.alwaysDrop = true; return s.and(a); }
- public Seq andnot2(Seq s, Seq a) { a.alwaysDrop = true; return s.andnot(a); }
-
//////////////////////////////////////////////////////////////////////////////
public class Context {
projects / sbp.git / blobdiff