tree-sitter-tiger/grammar.js

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function sepBy1(sep, rule) {
return seq(rule, repeat(seq(sep, rule)))
}
function sepBy(sep, rule) {
return optional(sepBy1(sep, rule))
}
const PREC = {
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assign: 6,
multiplicative: 5,
additive: 4,
comparative: 3,
and: 2,
or: 1,
};
module.exports = grammar({
name: "tiger",
// Ensure we don't extract keywords from tokens
word: ($) => $.identifier,
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conflicts: ($) => [
[$._lvalue, $.array_expression],
],
externals: ($) => [
// Nested comments need to be tokenized externally
$.comment,
],
extras: ($) => [
/( |\n|\r|\t)+/,
$.comment,
],
rules: {
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source_file: ($) => choice(
$._expr,
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optional($._declaration_chunks),
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),
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// Expressions {{{
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_expr: ($) => choice(
$.nil_literal,
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$.integer_literal,
$.string_literal,
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$.array_expression,
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$.record_expression,
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$._lvalue,
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$.function_call,
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$.unary_expression,
$.binary_expression,
$.sequence_expression,
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$.assignment_expression,
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$.if_expression,
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$.while_expression,
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$.for_expression,
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$.break_expression,
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$.let_expression,
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),
nil_literal: (_) => "nil",
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integer_literal: (_) => /[0-9]+/,
string_literal: ($) => seq(
'"',
repeat(choice($.escape_sequence, /[^"\\]+/)),
'"',
),
// NOTE: includes reserved identifiers
identifier: (_) => /[_a-zA-Z0-9]+/,
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escape_sequence: (_) => token.immediate(
seq(
"\\",
choice(
// Special escapes
choice("a", "b", "f", "n", "r", "t", "v"),
// Octal
/[0-3][0-7]{2}/,
// Hexadecimal
seq("x", /[0-9a-fA-F]{2}/),
// Escaped characters
choice("\\", '"'),
)
)
),
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_lvalue: ($) => choice(
$.identifier,
$.record_value,
$.array_value,
),
record_value: ($) => seq(
field("record", $._lvalue),
".",
field("field", $.identifier),
),
array_value: ($) => seq(
field("array", $._lvalue),
"[",
field("index", $._expr),
"]",
),
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function_call: ($) => seq(
field("function", $.identifier),
"(",
field("arguments", sepBy(",", $._expr)),
")",
),
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unary_expression: ($) => seq(
field("operator", alias("-", $.operator)),
field("expression", $._expr),
),
binary_expression: ($) => {
const table = [
[PREC.multiplicative, prec.left, choice("*", "/")],
[PREC.additive, prec.left, choice("+", "-")],
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// FIXME: comparisons should be non-associative
// See https://github.com/tree-sitter/tree-sitter/issues/761
[PREC.comparative, prec.left, choice(">=", "<=", "=", "<>", "<", ">")],
[PREC.and, prec.left, "&"],
[PREC.or, prec.left, "|"],
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];
return choice(
...table.map(
([priority, assoc, operator]) => assoc(
priority,
seq(
field("left", $._expr),
field("operator", alias(operator, $.operator)),
field("right", $._expr),
)
)
)
);
},
sequence_expression: ($) => seq("(", sepBy(";", $._expr), ")"),
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array_expression: ($) => seq(
field("type", $.identifier),
"[",
field("size", $._expr),
"]",
"of",
field("init", $._expr),
),
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record_expression: ($) => seq(
field("type", $.identifier),
"{",
sepBy(
",",
seq(
field("field", $.identifier),
"=",
field("init", $._expr),
),
),
"}",
),
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assignment_expression: ($) => prec.right(
PREC.assign,
seq(
field("left", $._lvalue),
":=",
field("right", $._expr),
),
),
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if_expression: ($) => prec.right(
seq(
"if",
field("condition", $._expr),
"then",
field("consequence", $._expr),
optional(
seq(
"else",
field("alternative", $._expr),
),
),
),
),
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while_expression: ($) => seq(
"while",
field("condition", $._expr),
"do",
field("body", $._expr),
),
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for_expression: ($) => seq(
"for",
field("index", $.identifier),
":=",
field("start", $._expr),
"to",
field("end", $._expr),
"do",
field("body", $._expr),
),
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break_expression: (_) => "break",
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let_expression: ($) => seq(
"let",
field("declarations", optional($._declaration_chunks)),
"in",
field("body", sepBy(";", $._expr)),
"end",
),
// }}}
// Declarations {{{
_declaration_chunks: ($) => repeat1($._declaration_chunk),
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_declaration_chunk: ($) => prec.left(
choice(
repeat1($.type_declaration),
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repeat1(choice($.function_declaration, $.primitive_declaration)),
$.variable_declaration,
$.import_declaration,
),
),
type_declaration: ($) => seq(
"type",
field("name", $.identifier),
"=",
field("value", $._type)
),
_type: ($) => choice(
$.type_alias,
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$.record_type,
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$.array_type,
),
type_alias: ($) => $.identifier,
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record_type: ($) => seq(
"{",
sepBy(",", $._typed_field),
"}",
),
_typed_field: ($) => seq(
field("name", $.identifier),
":",
field("type", $.identifier),
),
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array_type: ($) => seq(
"array",
"of",
field("element_type", $.identifier),
),
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function_declaration: ($) => seq(
"function",
$._function_declaration_common,
"=",
field("body", $._expr),
),
primitive_declaration: ($) => seq(
"primitive",
$._function_declaration_common,
),
_function_declaration_common: ($) => seq(
field("name", $.identifier),
field("parameters", $.parameters),
optional(seq(":", field("return_type", $.identifier))),
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),
parameters: ($) => seq(
"(",
sepBy(",", $._typed_field),
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")",
),
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variable_declaration: ($) => seq(
"var",
field("name", $.identifier),
optional(seq(":", field("type", $.identifier))),
":=",
field("value", $._expr),
),
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import_declaration: ($) => seq(
"import",
field("file", $.string_literal),
),
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// }}}
}
});
// vim: sw=2