Use arrayview for bit set

runtime/JavaScript/spec/BitSetSpec.js

@@ -0,0 +1,110 @@
+import BitSet from "../src/antlr4/misc/BitSet.js";
+
+describe('test BitSet', () => {
+
+    it("is empty", () => {
+        const bs = new BitSet();
+        expect(bs.length).toEqual(0);
+    })
+
+    it("sets 1 value", () => {
+        const bs = new BitSet();
+        bs.set(67);
+        expect(bs.length).toEqual(1);
+        expect(bs.get(67)).toBeTrue();
+    })
+
+    it("clears 1 value", () => {
+        const bs = new BitSet();
+        bs.set(67);
+        bs.clear(67)
+        expect(bs.length).toEqual(0);
+        expect(bs.get(67)).toBeFalse();
+    })
+
+    it("sets 2 consecutive values", () => {
+        const bs = new BitSet();
+        bs.set(67);
+        bs.set(68);
+        expect(bs.length).toEqual(2);
+        expect(bs.get(67)).toBeTrue();
+        expect(bs.get(68)).toBeTrue();
+    })
+
+    it("sets 2 close values", () => {
+        const bs = new BitSet();
+        bs.set(67);
+        bs.set(70);
+        expect(bs.length).toEqual(2);
+        expect(bs.get(67)).toBeTrue();
+        expect(bs.get(70)).toBeTrue();
+    })
+
+    it("sets 2 distant values", () => {
+        const bs = new BitSet();
+        bs.set(67);
+        bs.set(241);
+        expect(bs.length).toEqual(2);
+        expect(bs.get(67)).toBeTrue();
+        expect(bs.get(241)).toBeTrue();
+    })
+
+    it("combines 2 identical sets", () => {
+        const bs1 = new BitSet();
+        bs1.set(67);
+        const bs2 = new BitSet();
+        bs2.set(67);
+        bs1.or(bs2);
+        expect(bs1.length).toEqual(1);
+        expect(bs1.get(67)).toBeTrue();
+    })
+
+    it("combines 2 distinct sets", () => {
+        const bs1 = new BitSet();
+        bs1.set(67);
+        const bs2 = new BitSet();
+        bs2.set(69);
+        bs1.or(bs2);
+        expect(bs1.length).toEqual(2);
+        expect(bs1.get(67)).toBeTrue();
+        expect(bs1.get(69)).toBeTrue();
+    })
+
+    it("combines 2 overlapping sets", () => {
+        const bs1 = new BitSet();
+        bs1.set(67);
+        bs1.set(69);
+        const bs2 = new BitSet();
+        bs2.set(69);
+        bs2.set(71);
+        bs1.or(bs2);
+        expect(bs1.length).toEqual(3);
+        expect(bs1.get(67)).toBeTrue();
+        expect(bs1.get(69)).toBeTrue();
+        expect(bs1.get(71)).toBeTrue();
+    })
+
+    it("returns values", () => {
+        const bs = new BitSet();
+        bs.set(67);
+        bs.set(69);
+        const values = bs.values();
+        expect(values).toEqual([67, 69]);
+    })
+
+    it("counts bits", () => {
+        for(let i= 0; i <= 0xFF; i++) {
+            // count bits the slow but easy to understand way (Kernighan method)
+            let count1 = 0;
+            let value = i;
+            while(value) {
+                if(value & 1)
+                    count1++;
+                value >>= 1;
+            }
+            // count bits the fast way
+            const count2 = BitSet._bitCount(i);
+            expect(count2).toEqual(count1);
+        }
+    })
+})

runtime/JavaScript/src/antlr4/atn/LL1Analyzer.js

@@ -134,17 +134,17 @@ export default class LL1Analyzer {
                 return;
             }
             if (ctx !== PredictionContext.EMPTY) {
-                const removed = calledRuleStack.has(s.ruleIndex);
+                const removed = calledRuleStack.get(s.ruleIndex);
                 try {
-                    calledRuleStack.remove(s.ruleIndex);
+                    calledRuleStack.clear(s.ruleIndex);
                     // run thru all possible stack tops in ctx
                     for (let i = 0; i < ctx.length; i++) {
                         const returnState = this.atn.states[ctx.getReturnState(i)];
                         this._LOOK(returnState, stopState, ctx.getParent(i), look, lookBusy, calledRuleStack, seeThruPreds, addEOF);
                     }
                 }finally {
                     if (removed) {
-                        calledRuleStack.add(s.ruleIndex);
+                        calledRuleStack.set(s.ruleIndex);
                     }
                 }
                 return;
@@ -153,15 +153,15 @@ export default class LL1Analyzer {
         for(let j=0; j<s.transitions.length; j++) {
             const t = s.transitions[j];
             if (t.constructor === RuleTransition) {
-                if (calledRuleStack.has(t.target.ruleIndex)) {
+                if (calledRuleStack.get(t.target.ruleIndex)) {
                     continue;
                 }
                 const newContext = SingletonPredictionContext.create(ctx, t.followState.stateNumber);
                 try {
-                    calledRuleStack.add(t.target.ruleIndex);
+                    calledRuleStack.set(t.target.ruleIndex);
                     this._LOOK(t.target, stopState, newContext, look, lookBusy, calledRuleStack, seeThruPreds, addEOF);
                 } finally {
-                    calledRuleStack.remove(t.target.ruleIndex);
+                    calledRuleStack.clear(t.target.ruleIndex);
                 }
             } else if (t instanceof AbstractPredicateTransition ) {
                 if (seeThruPreds) {

runtime/JavaScript/src/antlr4/atn/ParserATNSimulator.js

@@ -1010,7 +1010,7 @@ export default class ParserATNSimulator extends ATNSimulator {
         let altToPred = [];
         for(let i=0;i<configs.items.length;i++) {
             const c = configs.items[i];
-            if(ambigAlts.has( c.alt )) {
+            if(ambigAlts.get( c.alt )) {
                 altToPred[c.alt] = SemanticContext.orContext(altToPred[c.alt] || null, c.semanticContext);
             }
         }
@@ -1039,7 +1039,7 @@ export default class ParserATNSimulator extends ATNSimulator {
         for (let i=1; i<altToPred.length;i++) {
             const pred = altToPred[i];
             // unpredicated is indicated by SemanticContext.NONE
-            if( ambigAlts!==null && ambigAlts.has( i )) {
+            if( ambigAlts!==null && ambigAlts.get( i )) {
                 pairs.push(new PredPrediction(pred, i));
             }
             if (pred !== SemanticContext.NONE) {
@@ -1173,7 +1173,7 @@ export default class ParserATNSimulator extends ATNSimulator {
         for(let i=0;i<predPredictions.length;i++) {
             const pair = predPredictions[i];
             if (pair.pred === SemanticContext.NONE) {
-                predictions.add(pair.alt);
+                predictions.set(pair.alt);
                 if (! complete) {
                     break;
                 }
@@ -1187,7 +1187,7 @@ export default class ParserATNSimulator extends ATNSimulator {
                 if (this.debug || this.dfa_debug) {
                     console.log("PREDICT " + pair.alt);
                 }
-                predictions.add(pair.alt);
+                predictions.set(pair.alt);
                 if (! complete) {
                     break;
                 }
@@ -1544,7 +1544,7 @@ export default class ParserATNSimulator extends ATNSimulator {
         let conflictingAlts = null;
         if (configs.uniqueAlt!== ATN.INVALID_ALT_NUMBER) {
             conflictingAlts = new BitSet();
-            conflictingAlts.add(configs.uniqueAlt);
+            conflictingAlts.set(configs.uniqueAlt);
         } else {
             conflictingAlts = configs.conflictingAlts;
         }

runtime/JavaScript/src/antlr4/atn/PredictionMode.js

@@ -511,7 +511,7 @@ const PredictionMode = {
                 alts = new BitSet();
                 configToAlts.set(cfg, alts);
             }
-            alts.add(cfg.alt);
+            alts.set(cfg.alt);
         });
         return configToAlts.getValues();
     },
@@ -532,7 +532,7 @@ const PredictionMode = {
                 alts = new BitSet();
                 m.set(c.state, alts);
             }
-            alts.add(c.alt);
+            alts.set(c.alt);
         });
         return m;
     },

runtime/JavaScript/src/antlr4/error/DiagnosticErrorListener.js

@@ -96,7 +96,7 @@ export default class DiagnosticErrorListener extends ErrorListener {
 		}
 		const result = new BitSet()
 		for (let i = 0; i < configs.items.length; i++) {
-			result.add(configs.items[i].alt);
+			result.set(configs.items[i].alt);
 		}
 		return `{${result.values().join(", ")}}`;
 	}

runtime/JavaScript/src/antlr4/misc/BitSet.js

@@ -8,31 +8,74 @@ import equalArrays from "../utils/equalArrays.js";
 export default class BitSet {
 
     constructor() {
-        this.data = [];
+        this.data = new Uint32Array(1);
     }
 
-    add(value) {
-        this.data[value] = true;
+    set(index) {
+        BitSet._checkIndex(index)
+        this._resize(index);
+        this.data[index >>> 5] |= 1 << index % 32;
     }
 
-    or(set) {
-        Object.keys(set.data).map(alt => this.add(alt), this);
+    get(index) {
+        BitSet._checkIndex(index)
+        const slot = index >>> 5;
+        if (slot >= this.data.length) {
+            return false;
+        }
+        return (this.data[slot] & 1 << index % 32) !== 0;
     }
 
-    remove(value) {
-        delete this.data[value];
+    clear(index) {
+        BitSet._checkIndex(index)
+        const slot = index >>> 5;
+        if (slot < this.data.length) {
+            this.data[index >>> 5] &= ~(1 << index);
+        }
     }
 
-    has(value) {
-        return this.data[value] === true;
+    or(set) {
+        const minCount = Math.min(this.data.length, set.data.length);
+        for (let k = 0; k < minCount; ++k) {
+            this.data[k] |= set.data[k];
+        }
+        if (this.data.length < set.data.length) {
+            this._resize((set.data.length << 5) - 1);
+            const c = set.data.length;
+            for (let k = minCount; k < c; ++k) {
+                this.data[k] = set.data[k];
+            }
+        }
     }
 
     values() {
-        return Object.keys(this.data);
+        const result = new Array(this.length);
+        let pos = 0;
+        const length = this.data.length;
+        for (let k = 0; k < length; ++k) {
+            let l = this.data[k];
+            while (l !== 0) {
+                const t = l & -l;
+                result[pos++] = (k << 5) + BitSet._bitCount(t - 1);
+                l ^= t;
+            }
+        }
+        return result;
     }
 
     minValue() {
-        return Math.min.apply(null, this.values());
+         for (let k = 0; k < this.data.length; ++k) {
+            let l = this.data[k];
+            if (l !== 0) {
+                let result = 0;
+                while ((l & 1) === 0) {
+                    result++;
+                    l >>= 1;
+                }
+                return result + (32 * k);
+            }
+        }
+        return 0;
     }
 
     hashCode() {
@@ -48,6 +91,33 @@ export default class BitSet {
     }
 
     get length(){
-        return this.values().length;
+        return this.data.map(l => BitSet._bitCount(l)).reduce((s,v) => s + v, 0);
+    }
+
+    _resize(index) {
+        const count = index + 32 >>> 5;
+        if (count <= this.data.length) {
+            return;
+        }
+        const data = new Uint32Array(count);
+        data.set(this.data);
+        data.fill(0, this.data.length);
+        this.data = data;
+    }
+
+    static _checkIndex(index) {
+        if(index < 0)
+            throw new RangeError("index cannot be negative");
+    }
+
+    static _bitCount(l) {
+        // see https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
+        let count = 0;
+        l = l - ((l >> 1) & 0x55555555);
+        l = (l & 0x33333333) + ((l >> 2) & 0x33333333);
+        l = (l + (l >> 4)) & 0x0f0f0f0f;
+        l = l + (l >> 8);
+        l = l + (l >> 16);
+        return count + l & 0x3f;
     }
 }