feat: add simple for-of loop (not intended for production usage)

src/java/me/topchetoeu/jscript/compilation/control/ForOfStatement.java

@@ -0,0 +1,73 @@
+package me.topchetoeu.jscript.compilation.control;
+
+import me.topchetoeu.jscript.common.Instruction;
+import me.topchetoeu.jscript.common.Location;
+import me.topchetoeu.jscript.common.Instruction.BreakpointType;
+import me.topchetoeu.jscript.compilation.CompileResult;
+import me.topchetoeu.jscript.compilation.Statement;
+
+public class ForOfStatement extends Statement {
+    public final String varName;
+    public final boolean isDeclaration;
+    public final Statement iterable, body;
+    public final String label;
+    public final Location varLocation;
+
+    @Override
+    public void declare(CompileResult target) {
+        body.declare(target);
+        if (isDeclaration) target.scope.define(varName);
+    }
+
+    @Override
+    public void compile(CompileResult target, boolean pollute) {
+        var key = target.scope.getKey(varName);
+
+        if (key instanceof String) target.add(Instruction.makeVar((String)key));
+
+        iterable.compile(target, true, BreakpointType.STEP_OVER);
+        target.add(Instruction.dup());
+        target.add(Instruction.loadVar("Symbol"));
+        target.add(Instruction.pushValue("iterator"));
+        target.add(Instruction.loadMember()).setLocation(iterable.loc());
+        target.add(Instruction.loadMember()).setLocation(iterable.loc());
+        target.add(Instruction.call(0)).setLocation(iterable.loc());
+
+        int start = target.size();
+        target.add(Instruction.dup());
+        target.add(Instruction.dup());
+        target.add(Instruction.pushValue("next"));
+        target.add(Instruction.loadMember()).setLocation(iterable.loc());
+        target.add(Instruction.call(0)).setLocation(iterable.loc());
+        target.add(Instruction.dup());
+        target.add(Instruction.pushValue("done"));
+        target.add(Instruction.loadMember()).setLocation(iterable.loc());
+        int mid = target.temp();
+
+        target.add(Instruction.pushValue("value"));
+        target.add(Instruction.loadMember()).setLocation(varLocation);
+        target.add(Instruction.storeVar(key)).setLocationAndDebug(iterable.loc(), BreakpointType.STEP_OVER);
+
+        body.compile(target, false, BreakpointType.STEP_OVER);
+
+        int end = target.size();
+
+        WhileStatement.replaceBreaks(target, label, mid + 1, end, start, end + 1);
+
+        target.add(Instruction.jmp(start - end));
+        target.add(Instruction.discard());
+        target.add(Instruction.discard());
+        target.set(mid, Instruction.jmpIf(end - mid + 1));
+        if (pollute) target.add(Instruction.pushUndefined());
+    }
+
+    public ForOfStatement(Location loc, Location varLocation, String label, boolean isDecl, String varName, Statement object, Statement body) {
+        super(loc);
+        this.varLocation = varLocation;
+        this.label = label;
+        this.isDeclaration = isDecl;
+        this.varName = varName;
+        this.iterable = object;
+        this.body = body;
+    }
+}

src/java/me/topchetoeu/jscript/compilation/parsing/Parsing.java

@@ -1777,6 +1777,46 @@ public class Parsing {
 
         return ParseRes.res(new ForInStatement(loc, nameLoc, labelRes.result, isDecl, nameRes.result, varVal, objRes.result, bodyRes.result), n);
     }
+    public static ParseRes<ForOfStatement> parseForOf(Filename filename, List<Token> tokens, int i) {
+        var loc = getLoc(filename, tokens, i);
+        int n = 0;
+
+        var labelRes = parseLabel(tokens, i + n);
+        var isDecl = false;
+        n += labelRes.n;
+
+        if (!isIdentifier(tokens, i + n++, "for")) return ParseRes.failed();
+        if (!isOperator(tokens, i + n++, Operator.PAREN_OPEN)) return ParseRes.error(loc, "Expected a open paren after 'for'.");
+
+        if (isIdentifier(tokens, i + n, "var")) {
+            isDecl = true;
+            n++;
+        }
+
+        var nameRes = parseIdentifier(tokens, i + n);
+        if (!nameRes.isSuccess()) return ParseRes.error(loc, "Expected a variable name for 'for' loop.");
+        var nameLoc = getLoc(filename, tokens, i + n);
+        n += nameRes.n;
+
+        if (!isIdentifier(tokens, i + n++, "of")) {
+            if (nameRes.result.equals("const")) return ParseRes.error(loc, "'const' declarations are not supported.");
+            else if (nameRes.result.equals("let")) return ParseRes.error(loc, "'let' declarations are not supported.");
+            else return ParseRes.error(loc, "Expected 'of' keyword after variable declaration.");
+        }
+
+        var objRes = parseValue(filename, tokens, i + n, 0);
+        if (!objRes.isSuccess()) return ParseRes.error(loc, "Expected a value.", objRes);
+        n += objRes.n;
+
+        if (!isOperator(tokens, i + n++, Operator.PAREN_CLOSE)) return ParseRes.error(loc, "Expected a closing paren after for.");
+
+
+        var bodyRes = parseStatement(filename, tokens, i + n);
+        if (!bodyRes.isSuccess()) return ParseRes.error(loc, "Expected a for body.", bodyRes);
+        n += bodyRes.n;
+
+        return ParseRes.res(new ForOfStatement(loc, nameLoc, labelRes.result, isDecl, nameRes.result, objRes.result, bodyRes.result), n);
+    }
     public static ParseRes<TryStatement> parseCatch(Filename filename, List<Token> tokens, int i) {
         var loc = getLoc(filename, tokens, i);
         int n = 0;
@@ -1833,6 +1873,7 @@ public class Parsing {
             parseSwitch(filename, tokens, i),
             parseFor(filename, tokens, i),
             parseForIn(filename, tokens, i),
+            parseForOf(filename, tokens, i),
             parseDoWhile(filename, tokens, i),
             parseCatch(filename, tokens, i),
             parseCompound(filename, tokens, i),