feat(#3706): Identify a Rule Where an Error Occurred

eo-parser/src/main/java/org/eolang/parser/ParsingErrors.java

@@ -26,9 +26,12 @@
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 import org.antlr.v4.runtime.BaseErrorListener;
+import org.antlr.v4.runtime.InputMismatchException;
 import org.antlr.v4.runtime.NoViableAltException;
+import org.antlr.v4.runtime.Parser;
 import org.antlr.v4.runtime.RecognitionException;
 import org.antlr.v4.runtime.Recognizer;
 import org.antlr.v4.runtime.Token;
@@ -43,6 +46,10 @@
  * Accumulates all parsing errors.
  *
  * @since 0.30.0
+ * @todo #3706:30min Split {@link ParsingErrors} into two classes.
+ *  Currently we use the same {@link ParsingErrors} class to accumulate all the parsing errors
+ *  despite their origin. This class should be split into two classes: one for parsing errors
+ *  {@link ParserErrors} and another for lexer errors {@link LexerErrors}.
  */
 final class ParsingErrors extends BaseErrorListener implements Iterable<Directive> {
 
@@ -83,19 +90,28 @@ public void syntaxError(
         final String msg,
         final RecognitionException error
     ) {
-        // @checkstyle MethodBodyCommentsCheck (20 lines)
-        // @todo #3332:30min Add more specific error messages.
-        //  Currently we write just "error: no viable alternative at input" for all errors.
-        //  It's better to use 'Recognizer<?, ?> recognizer' parameter of the current method
-        //  to retrieve more specific error messages.
-        if (error instanceof NoViableAltException) {
+        if (error instanceof NoViableAltException || error instanceof InputMismatchException) {
             final Token token = (Token) symbol;
+            final Parser parser = (Parser) recognizer;
+            final String rule = parser.getRuleInvocationStack().get(0);
+            final String[] names = parser.getRuleNames();
+            final String detailed;
+            if (names[EoParser.RULE_objects].equals(rule)) {
+                detailed = "Invalid object declaration";
+            } else if (names[EoParser.RULE_metas].equals(rule)) {
+                detailed = "Invalid meta declaration";
+            } else if (names[EoParser.RULE_program].equals(rule)) {
+                detailed = "Invalid program declaration";
+            } else {
+                detailed = "no viable alternative at input";
+            }
             this.errors.add(
                 new ParsingException(
                     String.format(
-                        "[%d:%d] %s:%n%s",
+                        "[%d:%d] %s: %s:%n%s",
                         line, position,
-                        "error: no viable alternative at input",
+                        "error",
+                        detailed,
                         new UnderlinedMessage(
                             this.line(line).orElse("EOF"),
                             position,
@@ -106,6 +122,15 @@ public void syntaxError(
                     line
                 )
             );
+        } else if (Objects.isNull(error)) {
+            this.errors.add(
+                new ParsingException(
+                    String.format(
+                        "[%d:%d] %s: %s", line, position, "error", msg
+                    ),
+                    line
+                )
+            );
         } else {
             this.errors.add(
                 new ParsingException(

eo-parser/src/main/java/org/eolang/parser/ParsingException.java

@@ -40,6 +40,15 @@ public final class ParsingException extends RuntimeException {
      */
     private final int place;
 
+    /**
+     * Ctor.
+     * @param msg Message
+     * @param line The place
+     */
+    public ParsingException(final String msg, final int line) {
+        this(msg, null, line);
+    }
+
     /**
      * Ctor.
      * @param msg Message

eo-parser/src/test/java/org/eolang/parser/EoSyntaxTest.java

@@ -264,7 +264,7 @@ void checksTypoPacks(final String yaml) {
         );
         Assumptions.assumeTrue(story.map().get("skip") == null);
         MatcherAssert.assertThat(
-            EoIndentLexerTest.TO_ADD_MESSAGE,
+            "We expect the error with correct line number was found",
             XhtmlMatchers.xhtml(story.after().toString()),
             XhtmlMatchers.hasXPaths("/program/errors/error/@line")
         );

eo-parser/src/test/resources/org/eolang/parser/eo-typos/binding-with-rho.yaml

@@ -22,7 +22,7 @@
 ---
 line: 2
 message: >-
-  [2:4] error: no viable alternative at input:
+  [2:4] error: Invalid object declaration:
     y:^
       ^
 input: |

eo-parser/src/test/resources/org/eolang/parser/eo-typos/broken-binding.yaml

@@ -21,6 +21,11 @@
 # SOFTWARE.
 ---
 line: 4
+# @todo #3706:30min Add exact location of the error in the message.
+#  This message is already quite clear, but it would be better if it included
+#  the exact location of the error.
+message: |-
+  Object binding can't be negative
 input: |
   # No comments
   [] > foo

eo-parser/src/test/resources/org/eolang/parser/eo-typos/broken-head.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 2
+message: |-
+  [2:7] error: Invalid object declaration:
+  [] > a [] > b [] > c [] > d hello world
+         ^
 input: |
   # No comments
   [] > a [] > b [] > c [] > d hello world

eo-parser/src/test/resources/org/eolang/parser/eo-typos/comment-in-method.yaml

@@ -21,6 +21,12 @@
 # SOFTWARE.
 ---
 line: 5
+# @todo #3706:30min The error message doesn't highlight the exact position of the
+#  comment. The error message should be updated to point to the exact position
+#  of the comment.
+message: |
+  [5:12] error: Invalid object declaration:
+      sprintwf
 input: |
   # No comments
   [args] > app

eo-parser/src/test/resources/org/eolang/parser/eo-typos/double-empty-lines.yaml

@@ -21,6 +21,12 @@
 # SOFTWARE.
 ---
 line: 4
+# @todo #3706:30min Cryptic error message is returned
+#  Cryptic error message is returned when there are two empty lines between metas.
+#  The error message should be more informative and should highlight the exact location
+#  of the error.
+message: |-
+  [4:0] error: extraneous input '\n' expecting {COMMENTARY, 'Q', 'QQ', '*', '$', '[', '(', '@', '^', BYTES, STRING, INT, FLOAT, HEX, NAME, TEXT}
 input: |
   # No comments.
   [args] > one

eo-parser/src/test/resources/org/eolang/parser/eo-typos/double-space-in-meta.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 1
+message: |-
+  [1:10] error: Invalid meta declaration:
+  +meta with  spaces
+            ^
 input: |
   +meta with  spaces
 

eo-parser/src/test/resources/org/eolang/parser/eo-typos/empty-line-between-metas.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 3
+message: |-
+  [3:0] error: Invalid object declaration:
+  +meta other
+  ^^^^^^^^^^
 input: |
   +meta smth
 

eo-parser/src/test/resources/org/eolang/parser/eo-typos/missing-empty-line-after-metas.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 3
+message: |-
+  [3:0] error: Invalid meta declaration:
+  [] > main
+  ^
 input: |
   +meta smth
   +meta other

eo-parser/src/test/resources/org/eolang/parser/eo-typos/not-empty-atoms.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 4
+message: |-
+  [4:-1] error: Invalid program declaration:
+    [] > inner
+  ^^^^^^^^^^^^
 input: |
   # No comments.
   [] > test /int

eo-parser/src/test/resources/org/eolang/parser/eo-typos/redundant-parentheses/simple-application-named.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 3
+message: |-
+  [3:-1] error: Invalid program declaration:
+  EOF
+  ^^^
 input: |
   1.add 1 > x
     (1.add 1) > y

eo-parser/src/test/resources/org/eolang/parser/eo-typos/redundant-parentheses/simple-application.yaml

@@ -21,6 +21,15 @@
 # SOFTWARE.
 ---
 line: 3
+# @todo #3706:30min Unreadable error message if program declaration is invalid.
+#  Improve error message for the case when a program declaration is invalid.
+#  The error message should be more informative and should point to the exact
+#  place in the input where the error occurred. Moreover it should be clear
+#  what to do to fix the error. 'simple-application-named.yaml' has the same issue.
+message: |-
+  [3:-1] error: Invalid program declaration:
+  EOF
+  ^^^
 input: |
   1.add 1 > x
     (1.add 1)

eo-parser/src/test/resources/org/eolang/parser/eo-typos/two-spaces.yaml

@@ -22,7 +22,7 @@
 ---
 line: 5
 message: >-
-  [5:2] error: no viable alternative at input:
+  [5:2] error: Invalid object declaration:
      *
     ^
 input: |

eo-parser/src/test/resources/org/eolang/parser/eo-typos/vmethod-after-happlication.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 2
+message: |-
+  [2:0] error: Invalid program declaration:
+  .z
+  ^
 input: |
   x y
   .z

eo-parser/src/test/resources/org/eolang/parser/eo-typos/vmethod-after-hmethod.yaml

@@ -21,6 +21,10 @@
 # SOFTWARE.
 ---
 line: 2
+message: |-
+  [2:0] error: Invalid program declaration:
+  .z
+  ^
 input: |
   x.y
   .z