antlr4 Add fixed grammars

Oct 12 '25 07:10 sumittlearnbay

Add non-overlapping ANTLR grammar examples for runtime tests

This commit introduces a set of nine non-obvious, non-overlapping grammars under runtime-testsuite/test/org/antlr/v4/test/runtime/antlr_grammars/ to demonstrate and validate diverse ANTLR 4 parsing features.

Included grammars:

Arithmetic.g4 — arithmetic expression parsing
BooleanExpr.g4 — boolean and logical expressions
CSVFlexible.g4 — flexible CSV handling with optional quotes
JSONMini.g4 — minimal JSON subset parser
MiniConfig.g4 — simple key-value configuration format
MiniMarkdown.g4 — lightweight markdown-like parser
MiniQuery.g4 — SQL-inspired query syntax
UnitExpr.g4 — unit-based mathematical expressions

All grammars are self-contained and compile successfully with ANTLR 4. Removed obsolete GrammarCompilationTest.java to fix build issues

Oct 12 '25 08:10 sumittlearnbay

successful check

Oct 12 '25 10:10 sumittlearnbay

For pedagogical purposes, your grammars should use EOF-terminated start rules. Since Antlr 4.7, the behavior of Antlr parsers has changed in how they parse at the point of an error: the parser backs up the input pointer to the last valid parse and reports success. For example, with Arithmetic.g4, the input 1+2 3 parses. (The parse tree is (expr (expr (INT "1")) (T__3 "+") (expr (INT "2"))).) This is not what most people expect, and it has resulted in dozens of issues in grammars-v4, other Github projects (e.g., Spice), and most recently in this repo (https://github.com/antlr/antlr4/issues/4890).

Also, I don't think your BooleanExpr grammar is a good example. Typically, the NOT operator has higher precedence than AND or OR, and textbooks on Boolean algebra follow this tradition. See https://bob.cs.sonoma.edu/IntroCompOrg-RPi/sec-balgebra.html#tb-boolprec. So, for input NOT TRUE OR FALSE, the parse tree should be (expr (expr (NOT "NOT") (expr (BOOL "TRUE"))) (OR "OR") (expr (BOOL "FALSE"))), not (expr (NOT "NOT") (expr (expr (BOOL "TRUE")) (OR "OR") (expr (BOOL "FALSE")))), which is what your grammar produces.

Oct 12 '25 10:10 kaby76

Add EOF-terminated fixed grammars following ANTLR 4.7+ and Boolean precedence standards

All grammars now terminate start rules with EOF for full input coverage, ensuring correct behavior under ANTLR 4.7+ (resolves partial parse acceptance issue).
BooleanExpr.g4 updated to follow textbook operator precedence: NOT > AND > OR (as per Table 5.1.4 in Robert G. Plantz, Introduction to Computer Organization).
Other grammars (Arithmetic, JSONMini, CSVFlexible, etc.) adjusted for clarity, non-overlap, and pedagogical consistency.
Removed test scaffolds for simplified inclusion in runtime-testsuite.

Signed-off-by: Sumit Pawar [email protected]

Oct 12 '25 11:10 sumittlearnbay

Add EOF-terminated fixed grammars following ANTLR 4.7+ and Boolean precedence standards

All grammars now terminate start rules with EOF for full input coverage, ensuring correct behavior under ANTLR 4.7+ (resolves partial parse acceptance issue).
BooleanExpr.g4 updated to follow textbook operator precedence: NOT > AND > OR (as per Table 5.1.4 in Robert G. Plantz, Introduction to Computer Organization).
Other grammars (Arithmetic, JSONMini, CSVFlexible, etc.) adjusted for clarity, non-overlap, and pedagogical consistency.
Removed test scaffolds for simplified inclusion in runtime-testsuite.

Signed-off-by: Sumit Pawar [email protected]

Oct 12 '25 12:10 sumittlearnbay