rtk-0.12: test-grammars/block.pg

grammar 'Block';

# A small bracket-structured grammar that exercises block-mode pretty layout
# (task 9b). It mirrors the shape of the c-compiler tutorial's c.pg: a function
# whose body is a brace-enclosed statement LIST, with statements that can
# nest another brace-enclosed block. Block-mode layout (--pp-layout=block)
# indents the statement lists - the indentation comes purely from the lists,
# not from the '{' '}' literals, so the same machinery indents begin/end-style
# blocks too (see pl0.pg). The flat default stays one line per construct.

Program = Prog: Function ;

Function = Func: 'fn' Ident '(' ParamList ')' Block ;

# A comma-separated list: an inline list (block mode keeps it on one line).
ParamList = Ident* ~ ',' ;

Block = Blk: '{' StatementList '}' ;

# A no-separator list of statements: a block list (block mode breaks and
# indents its elements).
StatementList = Statement* ;

Statement = Assign: Ident '=' Exp ';'
          | Return: 'return' Exp ';'
          | Nested: Block ;

Exp = Var: Ident
    | Num: num ;

Ident = Name: id ;

id = [a-zA-Z_][a-zA-Z0-9_]* ;
Int: num = [0-9]+ ;
Ignore: ws = [ \t\n\r]+ ;