Implement basic error recovery

.vscode/launch.json

@@ -38,7 +38,7 @@
             "request": "launch",
             "mainClass": "org.rascalmpl.shell.RascalShell",
             "projectName": "rascal",
-            "cwd" : "${workspaceFolder}/../rascal-tutor",
+            "cwd": "${workspaceFolder}/../rascal-tutor",
             "vmArgs": "-Xss80m -Xmx2g -ea"
         },
         {

src/org/rascalmpl/interpreter/Evaluator.java

@@ -989,7 +989,7 @@
         IMap syntaxDefinition = curMod.getSyntaxDefinition();
         IMap grammar = (IMap) getParserGenerator().getGrammarFromModules(getMonitor(), curMod.getName(), syntaxDefinition).get("rules");
         IConstructor reifiedType = vf.reifiedType(dummy, grammar);
-        return vf.parsers(reifiedType, vf.bool(false), vf.bool(false), vf.bool(false), vf.set()); 
+        return vf.parsers(reifiedType, vf.bool(false), vf.bool(false), vf.bool(false), vf.bool(false), vf.set()); 
     }
 
     private Result<IValue> evalMore(String command, ISourceLocation location)

src/org/rascalmpl/library/Prelude.java

@@ -2377,20 +2377,24 @@
 
 	protected final TypeReifier tr;
 
+	public IFunction parser(IValue start,  IBool allowAmbiguity, IBool allowRecovery, IBool hasSideEffects, ISet filters) {
+	    return rascalValues.parser(start, allowAmbiguity, allowRecovery, hasSideEffects, values.bool(false), filters);
+	}
+
 	public IFunction parser(IValue start,  IBool allowAmbiguity, IBool hasSideEffects, ISet filters) {
-	    return rascalValues.parser(start, allowAmbiguity, hasSideEffects, values.bool(false), filters);
+	    return rascalValues.parser(start, allowAmbiguity, values.bool(false), hasSideEffects, values.bool(false), filters);
 	}
 
-	public IFunction firstAmbiguityFinder(IValue start, IBool hasSideEffects, ISet filters) {
-	    return rascalValues.parser(start, values.bool(true), hasSideEffects, values.bool(true), filters);
+	public IFunction firstAmbiguityFinder(IValue start, IBool allowRecovery, IBool hasSideEffects, ISet filters) {
+	    return rascalValues.parser(start, values.bool(true), allowRecovery, hasSideEffects, values.bool(true), filters);
 	}
 
-	public IFunction parsers(IValue start,  IBool allowAmbiguity, IBool hasSideEffects, ISet filters) {
-        return rascalValues.parsers(start, allowAmbiguity, hasSideEffects, values.bool(false), filters);
+	public IFunction parsers(IValue start,  IBool allowAmbiguity, IBool allowRecovery, IBool hasSideEffects, ISet filters) {
+        return rascalValues.parsers(start, allowAmbiguity, allowRecovery, hasSideEffects, values.bool(false), filters);
     }
 
-	public IFunction firstAmbiguityFinders(IValue start, IBool hasSideEffects, ISet filters) {
-        return rascalValues.parsers(start, values.bool(true), hasSideEffects, values.bool(true), filters);
+	public IFunction firstAmbiguityFinders(IValue start, IBool allowRecovery, IBool hasSideEffects, ISet filters) {
+        return rascalValues.parsers(start, values.bool(true), allowRecovery, hasSideEffects, values.bool(true), filters);
     }
 
 	public void storeParsers(IValue start, ISourceLocation saveLocation) {
@@ -2405,18 +2409,18 @@
 		}
 	}
 
-	public IFunction loadParsers(ISourceLocation savedLocation, IBool allowAmbiguity, IBool hasSideEffects, ISet filters) {
+	public IFunction loadParsers(ISourceLocation savedLocation, IBool allowAmbiguity, IBool allowRecovery, IBool hasSideEffects, ISet filters) {
 		try {
-			return rascalValues.loadParsers(savedLocation, allowAmbiguity, hasSideEffects, values.bool(false), filters);
+			return rascalValues.loadParsers(savedLocation, allowAmbiguity, allowRecovery, hasSideEffects, values.bool(false), filters);
 		}
 		catch (IOException | ClassNotFoundException e) {
 			throw RuntimeExceptionFactory.io(e.getMessage());
 		}
 	}
 
-	public IFunction loadParser(IValue grammar, ISourceLocation savedLocation, IBool allowAmbiguity, IBool hasSideEffects, ISet filters) {
+	public IFunction loadParser(IValue grammar, ISourceLocation savedLocation, IBool allowRecovery, IBool allowAmbiguity, IBool hasSideEffects, ISet filters) {
 		try {
-			return rascalValues.loadParser(grammar, savedLocation, allowAmbiguity, hasSideEffects, values.bool(false), filters);
+			return rascalValues.loadParser(grammar, savedLocation, allowAmbiguity, allowRecovery, hasSideEffects, values.bool(false), filters);
 		}
 		catch (IOException | ClassNotFoundException e) {
 			throw RuntimeExceptionFactory.io(e.getMessage());

src/org/rascalmpl/library/lang/rascal/tests/recovery/BasicRecoveryTests.rsc

@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) 2024, NWO-I Centrum Wiskunde & Informatica (CWI)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ **/
+
+module lang::rascal::tests::recovery::BasicRecoveryTests
+
+import ParseTree;
+
+layout Layout = [\ ]* !>> [\ ];
+
+syntax S = T;
+
+syntax T = ABC End;
+syntax ABC = 'a' 'b' 'c';
+syntax End = "$";
+
+private Tree parseS(str input, bool visualize=false)
+    = parser(#S, allowRecovery=true, allowAmbiguity=true)(input, |unknown:///?visualize=<"<visualize>">|);
+
+test bool basicOk() {
+    return !hasErrors(parseS("a b c $", visualize=true));
+}
+
+test bool abx() {
+    Tree t = parseS("a b x $", visualize=true);
+    return getErrorText(findFirstError(defaultErrorDisambiguationFilter(t))) == "x ";
+}
+
+test bool axc() {
+    Tree t = parseS("a x c $", visualize=true);
+    return getErrorText(findFirstError(t)) == "x c";
+}
+
+test bool ax() {
+    Tree t = parseS("a x $", visualize=true);
+    return getErrorText(findFirstError(t)) == "x ";
+}

src/org/rascalmpl/library/lang/rascal/tests/recovery/ListRecoveryTests.rsc

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2024, NWO-I Centrum Wiskunde & Informatica (CWI)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ **/
+
+module lang::rascal::tests::recovery::ListRecoveryTests
+
+import ParseTree;
+import IO;
+
+layout Layout = [\ ]* !>> [\ ];
+
+syntax S = T End;
+
+syntax T = { AB "," }*;
+syntax AB = "a" "b";
+syntax End = "$";
+
+Tree parseList(str s, bool visualize=false) {
+    return parser(#S, allowRecovery=true, allowAmbiguity=true)(s, |unknown:///?visualize=<"<visualize>">|);
+}
+
+test bool listOk() {
+    return !hasErrors(parseList("a b , a b , a b $", visualize=true));
+}
+
+test bool listTypo() {
+    Tree t = parseList("a b, a x, ab $", visualize=true);
+    return hasErrors(t);
+}
+
+test bool listTypoWs() {
+    Tree t = parseList("a b , a x , a b $", visualize=true);
+    return hasErrors(t);
+}

src/org/rascalmpl/library/lang/rascal/tests/recovery/NestedRecoveryTests.rsc

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2024, NWO-I Centrum Wiskunde & Informatica (CWI)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ **/
+
+module lang::rascal::tests::recovery::NestedRecoveryTests
+
+import ParseTree;
+import IO;
+
+layout Layout = [\ ]* !>> [\ ];
+
+syntax S = T;
+
+syntax T = A B C;
+
+syntax A = "a";
+syntax B = "b" "b";
+syntax C = "c";
+
+private Tree parseS(str input, bool visualize=false)
+    = parser(#S, allowRecovery=true, allowAmbiguity=true)(input, |unknown:///?visualize=<"<visualize>">|);
+
+test bool nestedOk() {
+    return !hasErrors(parseS("a b b c"));
+}
+
+test bool nestedTypo() {
+    Tree t = parseS("a b x c");
+    return getErrorText(findFirstError(defaultErrorDisambiguationFilter(t))) == "x ";
+}

src/org/rascalmpl/library/lang/rascal/tests/recovery/PicoRecoveryTests.rsc

@@ -0,0 +1,111 @@
+/**
+ * Copyright (c) 2024, NWO-I Centrum Wiskunde & Informatica (CWI)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ **/
+
+module lang::rascal::tests::recovery::PicoRecoveryTests
+
+import lang::pico::\syntax::Main;
+
+import ParseTree;
+import IO;
+
+Tree parsePico(str input, bool visualize=false)
+    = parser(#Program, allowRecovery=true, allowAmbiguity=true)(input, |unknown:///?visualize=<"<visualize>">|);
+
+test bool picoOk() {
+    t = parsePico("begin declare input : natural,
+              output : natural,
+              repnr : natural,
+              rep : natural;
+      input := 14;
+      output := 0;
+      while input - 1 do
+          rep := output;
+          repnr := input;
+          while repnr - 1 do
+             output := output + rep;
+             repnr := repnr - 1
+          od;
+          input := input - 1
+      od
+end");
+    return !hasErrors(t);
+}
+
+test bool picoTypo() {
+    t = parsePico("begin declare input : natural,
+              output : natural,
+              repnr : natural,
+              rep : natural;
+      input := 14;
+      output := 0;
+      while input - 1 do
+          rep := output;
+          repnr := input;
+          while repnr - 1 do
+             output := output x rep;
+             repnr := repnr - 1
+          od;
+          input := input - 1
+      od
+end");
+    Tree error = findFirstError(defaultErrorDisambiguationFilter(t));
+    return getErrorText(error) == "output x rep";
+}
+
+test bool picoMissingSemi() {
+    t = parsePico("begin declare input : natural,
+              output : natural,
+              repnr : natural,
+              rep : natural;
+      input := 14;
+      output := 0;
+      while input - 1 do
+          rep := output;
+          repnr := input;
+          while repnr - 1 do
+             output := output + rep;
+             repnr := repnr - 1
+          od
+          input := input - 1
+      od
+end");
+    Tree error = findFirstError(defaultErrorDisambiguationFilter(t));
+    return getErrorText(error) == "input := input - 1\n      od";
+}
+
+test bool picoTypoSmall() {
+    t = parsePico(
+"begin declare;
+  while input do
+    input x= 14;
+    output := 0
+  od
+end");
+
+    Tree error = findFirstError(defaultErrorDisambiguationFilter(t));
+    return getErrorText(error) == "x= 14";
+}
+
+test bool picoMissingSemiSmall() {
+    t = parsePico(
+"begin declare;
+  while input do
+    input := 14
+    output := 0
+  od
+end");
+
+    Tree error = findFirstError(defaultErrorDisambiguationFilter(t));
+    return getErrorText(error) == "output := 0\n  od";
+}