From 863a6ed0ad723e06c76f392d4fb3a5f6bd22863c Mon Sep 17 00:00:00 2001
From: Jun Kawasaki <jun784@gmail.com>
Date: Tue, 6 Oct 2026 13:01:11 +0900
Subject: docs: add Japanese translations for all chapters

---
 chapter04/docs/04-grammar.ja.md | 81 +++++++++++++++++++++++++++++++++++++++++
 chapter04/docs/04-grammar.md    |  2 +
 2 files changed, 83 insertions(+)
 create mode 100644 chapter04/docs/04-grammar.ja.md

(limited to 'chapter04/docs')

diff --git a/chapter04/docs/04-grammar.ja.md b/chapter04/docs/04-grammar.ja.md
new file mode 100644
index 00000000..b8b6bff5
--- /dev/null
+++ b/chapter04/docs/04-grammar.ja.md
@@ -0,0 +1,81 @@
+# 第4章の文法
+
+[English](04-grammar.md) | 日本語
+
+この文書は [原文](04-grammar.md) の日本語訳です。
+
+> 訳注: 原文の見出しは「Grammar for Chapter 1」ですが、このファイルは第4章に属するため、訳の見出しは第4章としています。文法は原文のまま保持しています。
+
+
+[第4章に戻る](../README.ja.md)
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+    : statement+ EOF
+    ;
+
+statement
+    : returnStatement
+    | declStatement
+    | blockStatment
+    | expressionStatement
+    ;
+
+
+expressionStatement
+    : IDENTIFIER '=' expression ';'
+    ;
+
+blockStatement
+    : '{' statement+ '}'
+    ;
+
+declStatement
+    : 'int' IDENTIFIER '=' expression ';'
+    ;
+
+returnStatement
+    : 'return' expression ';'
+    ;
+
+expression
+    : comparisonExpression
+    ;
+
+comparisonExpression
+    : additiveExpression (('==' | '!='| '>'| '<'| '>='| '<=') additiveExpression)*
+    ;
+
+additiveExpression
+    : multiplicativeExpression (('+' | '-') multiplicativeExpression)*
+    ;
+
+multiplicativeExpression
+    : unaryExpression (('*' | '/') unaryExpression)*
+    ;
+
+unaryExpression
+    : ('-') unaryExpression
+    | primaryExpression
+    ;
+
+primaryExpression
+    : IDENTIFIER
+    | INTEGER_LITERAL
+    | '(' expression ')'
+    ;
+
+INTEGER_LITERAL
+    : [1-9][0-9]*
+    | [0]
+    ;
+
+IDENTIFIER
+    : NON_DIGIT (NON_DIGIT | DIGIT)*
+    ;
+
+NON_DIGIT: [a-zA-Z_];
+DEC_DIGIT: [0-9];
+```
diff --git a/chapter04/docs/04-grammar.md b/chapter04/docs/04-grammar.md
index 0600679e..3ea27850 100644
--- a/chapter04/docs/04-grammar.md
+++ b/chapter04/docs/04-grammar.md
@@ -1,5 +1,7 @@
 # Grammar for Chapter 1
 
+English | [日本語](04-grammar.ja.md)
+
 ```antlrv4
 grammar SimpleLanguage;
 
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