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|
/* Demonstrates use of semantic whitespace pseudo-tokens. */
%start prog
%ebnf
%options token-stack
%% /* language grammar */
prog
: proglist ENDOFFILE
{ console.log("AST: %j", $proglist); }
;
proglist
: proglist stmt
{ $proglist.push($stmt); $$ = $proglist; }
| stmt
{ $$ = [$stmt]; }
;
if_stmt
: IF LPAREN expr RPAREN COLON stmt_block
{ $$ = [ "if", $expr, $stmt_block ]; }
| IF LPAREN expr RPAREN COLON stmt_block ELSE COLON stmt_block
{ $$ = [ "if", $expr, $6, $9 ]; }
;
print_stmt
: PRINT STRING
{ $$ = ["print", $2]; }
;
stmt
: if_stmt
| print_stmt
;
stmt_list
: stmt
{ $$ = ["stmt_list", $stmt]; }
| stmt_list stmt
{ $stmt_list.push($stmt); $$ = $stmt_list; }
;
stmt_block
: INDENT stmt_list DEDENT
{ $$ = $stmt_list; }
;
atom
: ID
{ $$ = ["id", $1]; }
| NATLITERAL
{ $$ = ["natlit", $1]; }
| LPAREN expr RPAREN
{ $$ = ["expr", $2]; }
;
expr
: atom
| expr PLUS atom
{ $expr.push(["plus", $atom]); $$ = $expr; }
| expr MINUS atom
{ $expr.push(["minus", $atom]); $$ = $expr; }
;
|
