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+# Grammar for Chapter 25
+
+English | [日本語](25-grammar.ja.md)
+
+```antlrv4
+grammar SimpleLanguage;
+
+// Name lookup, assignable operands, type compatibility, and access permissions
+// are checked by the compiler in addition to these syntax rules.
+// A file is a compilation unit; its path supplies its namespace.
+// Qualified names resolve nested types and other units without an import keyword.
+program : statement* EOF ;
+
+block : '{' statement* '}' ;
+
+statement
+    : block
+    | returnStatement
+    | ifStatement
+    | whileStatement
+    | forStatement
+    | breakStatement
+    | continueStatement
+    | structDeclaration
+    | declaration ';'
+    | assignment ';'
+    | ';'
+    ;
+
+returnStatement   : 'return' assignment ';' ;
+ifStatement       : 'if' '(' assignment ')' statement ('else' statement)? ;
+whileStatement    : 'while' '(' assignment ')' statement ;
+breakStatement    : 'break' ';' ;
+continueStatement : 'continue' ';' ;
+
+forStatement
+    : 'for' '(' (declaration | assignment)? ';' assignment? ';' assignment? ')' statement
+    ;
+
+structDeclaration : 'struct' IDENTIFIER '{' structMember* '}' ';' ;
+structMember : constructorDeclaration | methodDeclaration | statement ;
+
+// The constructor name must match the enclosing struct's name.
+constructorDeclaration : 'new' IDENTIFIER '=' functionExpression ';' ;
+
+// A method is an ordinary fixed function binding in a struct definition.
+// The compiler supplies self; it is not written in parameterList.
+// Function types and expressions both receive their implicit receiver here.
+methodDeclaration : 'val' bindingModifier? IDENTIFIER '=' functionExpression ';' ;
+
+declaration : declarationType binding (',' binding)* ;
+declarationType : type | 'var' | 'val' ;
+binding : bindingModifier? IDENTIFIER ('=' initializer)? ;
+bindingModifier : '!' | '~' ;
+// A declaration initializer consisting of the string "C" declares an extern
+// symbol: a function, or explicit numeric native storage. Ordinary strings
+// elsewhere are array-valued expressions.
+initializer : assignment ;
+
+// The prefix qualifies the named struct reference, not an enclosing array.
+// Each [] / [~] suffix qualifies its own array layer. ? requires a reference.
+type
+    : functionType
+    | primitiveType typeSuffix*
+    | accessModifier? typeName typeSuffix*
+    ;
+accessModifier : '!' | '~' ;
+typeSuffix : '?' | '[]' | '[~]' ;
+typeName : IDENTIFIER ('.' IDENTIFIER)* ;
+
+primitiveType
+    : 'int' | 'i8' | 'i16' | 'i32' | 'i64'
+    | 'u1' | 'u8' | 'u16' | 'u32' | 'byte' | 'bool'
+    | 'flt' | 'f32' | 'f64'
+    ;
+
+assignment : expression (assignmentOperator assignment)? ;
+assignmentOperator
+    : '=' | '+=' | '-=' | '*=' | '/=' | '&=' | '|=' | '^='
+    | '<<=' | '>>=' | '>>>='
+    ;
+
+expression : logicalExpression ('?' assignment (':' assignment)?)? ;
+
+// Both logical operators short-circuit and associate to the right here.
+logicalExpression : bitwiseExpression (('&&' | '||') logicalExpression)? ;
+
+bitwiseExpression
+    : equalityExpression (('&' | '|' | '^') equalityExpression)*
+    ;
+
+equalityExpression : comparisonExpression (('==' | '!=') comparisonExpression)* ;
+
+// Chained comparisons test adjacent operands and short-circuit. A chain must
+// keep its direction; equality has lower precedence and does not join a chain.
+comparisonExpression
+    : shiftExpression
+      ( (('<' | '<=') shiftExpression)+ | (('>' | '>=') shiftExpression)+ )?
+    ;
+
+shiftExpression
+    : additiveExpression (('<<' | '>>' | '>>>') additiveExpression)*
+    ;
+
+additiveExpression
+    : multiplicativeExpression (('+' | '-') multiplicativeExpression)*
+    ;
+
+multiplicativeExpression
+    : unaryExpression (('*' | '/') unaryExpression)*
+    ;
+
+unaryExpression
+    : ('-' | '!') unaryExpression
+    | updateOperator IDENTIFIER
+    | postfixExpression
+    ;
+
+// Prefix updates require a local name; postfix updates also allow fields
+// and array elements. All updates require an assignable operand.
+updateOperator : '++' | '--' ;
+postfixExpression : primaryExpression postfixSuffix* updateOperator? ;
+postfixSuffix : '.' IDENTIFIER | '[' assignment ']' | '#' | callSuffix | methodCallSuffix ;
+
+// For a fixed function-valued member, object.name(args) passes object as self.
+// This overlaps ordinary field selection followed by a call syntactically;
+// name/type resolution determines which call form applies.
+methodCallSuffix : '.' IDENTIFIER callSuffix ;
+
+primaryExpression
+    : INTEGER_LITERAL
+    | FLOAT_LITERAL
+    | STRING_LITERAL
+    | CHARACTER_LITERAL
+    | 'true'
+    | 'false'
+    | 'null'
+    | IDENTIFIER
+    | '(' assignment ')'
+    | newExpression
+    | functionExpression
+    ;
+
+// A function is an expression bound with an ordinary declaration.
+// Its last statement supplies the implicit result; return can exit earlier.
+functionExpression : '{' parameterList? '->' statement* '}' ;
+parameterList : (parameter ','?)+ ;
+parameter : type bindingModifier? IDENTIFIER ;
+
+// Function types have unnamed, space-separated argument types.
+// {int} is the zero-argument type; its function expression still uses ->.
+functionType
+    : '{' type+ '->' type '}' '?'?
+    | '{' type '}' '?'?
+    ;
+
+callSuffix : '(' argumentList? ')' ;
+argumentList : assignment (',' assignment)* ','? ;
+
+// Allocation invokes the declared constructor; inline initializer blocks from
+// earlier chapters are replaced by constructor arguments.
+newExpression : 'new' type ('[' assignment ']' | callSuffix)? ;
+
+INTEGER_LITERAL : '0' | [1-9] DIGIT* ;
+FLOAT_LITERAL : DIGIT+ ('.' DIGIT* ('e' DIGIT+)? | 'e' '-'? DIGIT+) ;
+STRING_LITERAL : '"' (ESCAPE | ~["\\])* '"' ;
+CHARACTER_LITERAL : '\'' (ESCAPE | ~['\\]) '\'' ;
+fragment ESCAPE : '\\' [0ntr\\'"] ;
+IDENTIFIER : NON_DIGIT (NON_DIGIT | DIGIT)* ;
+fragment NON_DIGIT : [a-zA-Z_] ;
+fragment DIGIT : [0-9] ;
+WHITESPACE : [ \t\r\n]+ -> skip ;
+LINE_COMMENT : '//' ~[\r\n]* -> skip ;
+BLOCK_COMMENT : '/*' .*? '*/' -> skip ;
+```