better error message

[sbp.git] / src / edu / berkeley / sbp / meta / MetaGrammarBindings.java

diff --git a/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java b/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java
index 40f3e39..b0b86da 100644 (file)
--- a/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java
+++ b/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java
@@ -79,9 +79,8 @@ public class MetaGrammarBindings extends AnnotationGrammarBindings {
                 Seq[] group = sequences[i];
                 Union u2 = new Union(null, false);
                 if (sequences.length==1) u2 = u;
-                for(int j=0; j<group.length; j++) {
+                for(int j=0; j<group.length; j++)
                     group[j].build(cx, u2, cnt);
-                }
                 if (sequences.length==1) break;
                 Sequence seq = Sequence.create(u2);
                 for(Sequence s : bad2) seq = seq.andnot(s);
@@ -196,7 +195,7 @@ public class MetaGrammarBindings extends AnnotationGrammarBindings {
         public Seq(ElementNode e) { this(new ElementNode[] { e }); }
         public Seq(ElementNode[] elements) { this.elements = elements; }
         public Atom toAtom(Context cx) {
-            if (elements.length != 1) throw new Error("FIXME");
+            if (elements.length != 1) throw new Error("you attempted to use ->, **, ++, or a similar character-class operator on a [potentially] multicharacter production");
             return elements[0].toAtom(cx);
         }
         public Seq tag(String tag) { this.tag = prefix+tag; return this; }
@@ -267,6 +266,10 @@ public class MetaGrammarBindings extends AnnotationGrammarBindings {
     public static @bind.as("Elements")  Seq  seq2(ElementNode[] elements)               { return new Seq(elements); }
     public static @bind.as        Seq  psx(Seq s)                        { return s; }
     public static @bind.as(":")   ElementNode   colon(String s, ElementNode e)             { return new Label(s, e); }
+    public static @bind.as("{") ElementNode   leftBrace() {
+        return new Drop(new CharClass(new Range[] { new Range(CharAtom.left, CharAtom.left) })); }
+    public static @bind.as("}") ElementNode   rightBrace() {
+        return new Drop(new CharClass(new Range[] { new Range(CharAtom.right, CharAtom.right) })); }
     public static @bind.as(")")   void close(String foo)                 { throw new Error("not supported"); }
     public static @bind.as("()")  ElementNode   epsilon()                         { return new Constant(epsilon); }
 
@@ -390,15 +393,19 @@ public class MetaGrammarBindings extends AnnotationGrammarBindings {
     public static @bind.as("~")   ElementNode tilde(final ElementNode e) {
         return new ElementNodeWrapper(e) {
                 public Atom toAtom(Context cx) {
-                    return infer((Topology<Character>)e.toAtom(cx).complement().minus(CharAtom.braces));
+                    return infer((Topology<Character>)e.toAtom(cx).complement()/*.minus(CharAtom.braces)*/);
                 }
                 public Element build(Context cx, NonTerminalNode cnt) {
-                    return infer((Topology<Character>)e.toAtom(cx).complement().minus(CharAtom.braces));
+                    return infer((Topology<Character>)e.toAtom(cx).complement()/*.minus(CharAtom.braces)*/);
                 } }; }
 
     public static @bind.as("Word")        String word(String s) { return s; }
     public static @bind.as("Quoted")      String quoted(String s) { return s; }
-    public static @bind.as("escaped")     String c(char c) { return c+""; }
+    public static @bind.as("escaped")     String c(char c) {
+        if (c=='{') return CharAtom.left+"";
+        if (c=='}') return CharAtom.right+"";
+        return c+"";
+    }
     public static @bind.as("EmptyString") String emptystring() { return ""; }
     public static @bind.as("\n")          String retur() { return "\n"; }
     public static @bind.as("\r")          String lf() { return "\r"; }