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Flesh Out P4 Grammar

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Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
This commit is contained in:
Will Hawkins
2026-01-17 00:02:43 -05:00
parent 08beba6cb1
commit c78afa5418
5 changed files with 360 additions and 33 deletions
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tree-sitter-p4/grammar.js
+44 -21
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@@ -10,36 +10,31 @@
export default grammar({
name: 'p4',
rules: {
// TODO: add the actual grammar rules
// Start symbol
p4program: $ => optional(repeat($.declaration)),
declaration: $ => $.parserDeclaration,
parserTypeDeclaration: $ => seq(optional($.annotations), $.parser, field('parser_name', $.identifier), optional($.typeParameters), '(', optional($.nonEmptyParameterList), ')'),
//parserDeclaration: $ => seq($.parserTypeDeclaration, $.optConstructorParameters, '{', $.parserLocalElements, $.parserStates, '}'),
parserDeclaration: $ => seq($.parserTypeDeclaration, optional($.constructorParameters), '{', seq(optional($.parserLocalElements), $.parserStates), '}'),
// Common
// Common - Parameters
typeParameters: $ => seq('<', $.typeParameterList, '>'),
typeParameterList: $ => choice("[a-z]+", seq($.typeParameterList, ',', "[a-z]+")),
nonEmptyParameterList: $ => choice($.parameter, seq($.nonEmptyParameterList, ',', $.parameter)),
parameterList: $ => choice($.parameter, seq($.parameterList, ',', $.parameter)),
parameter: $ => choice(seq(optional($.annotations), optional($.direction), $.typeRef, $.identifier), seq(optional($.annotations), optional($.direction), $.typeRef, $.identifier, '=', $.expression)),
direction: $ => choice($.in, $.out, $.inout),
// Common - Types
typeRef: $ => $.baseType,
baseType: $ => choice($.bool, $.error, $.string, $.int, $.bit /* omitting "templated" types" */),
constructorParameters: $ => seq('(', optional($.parameterList), ')'),
constructorParameters: $ => seq('(', optional($.nonEmptyParameterList), ')'),
// Common - Parsers
parserType: $ => seq(optional($.annotations), $.parser, field('parser_name', $.identifier), optional($.typeParameters), '(', optional($.parameterList), ')'),
parserLocalElements: $ => choice(seq($.parserLocalElements, $.parserLocalElement)),
parserStates: $ => choice($.parserState, seq($.parserStates, $.parserState)),
// parserState: $ => seq(optional($.annotations), $.state, $.identifier , '{', $.parserStatements, $.transitionStatement, '}'),
parserState: $ => seq(optional($.annotations), $.state, $.identifier, '{', optional($.todo), '}'),
// Nothing, for now.
//parserLocalElement: $ => choice(constantDeclaration | variableDeclaration | instantiation | valueSetDeclaration)
parserState: $ => seq(optional($.annotations), $.state, $.identifier, '{', optional($.parserStatements), $.parserTransitionStatement, $.semicolon, '}'),
parserLocalElement: $ => choice($.todo),
selectBody: $ => repeat1(seq($.selectCase, $.semicolon)),
selectCase: $ => seq($.keysetExpression, $.colon, $.identifier),
annotations: $ => choice($.annotation, seq($.annotations, $.annotation)),
@@ -47,7 +42,37 @@ export default grammar({
annotation: $ => choice(seq('@', "[a-z]+"), seq('@', "[a-z]+", '(', /* empty for now*/ ')'), seq('@', "[a-z]+", '[', /* empty for now */ ']')),
// Declarations
declaration: $ => seq(choice($.parserDeclaration, $.parserTypeDeclaration), $.semicolon),
// Make separate productions for the parser type and the parser type declaration because the latter can have type parameters.
parserTypeDeclaration: $ => seq(optional($.annotations), $.parser, field('parser_name', $.identifier), optional($.typeParameters), '(', optional($.parameterList), ')'),
parserDeclaration: $ => seq($.parserType, optional($.constructorParameters), '{', seq(optional($.parserLocalElements), $.parserStates), '}'),
// Statements
// General statements
statements: $ => repeat1(seq($.statement, $.semicolon)),
statement: $ => choice($.conditionalStatement, $.blockStatement, $.expressionStatement),// Limited, so far.
blockStatement: $ => seq(optional($.annotations), '{', optional($.statements), '}'),
conditionalStatement: $ => choice(prec(1, seq($.if, '(', $.expression, ')', $.statement)), prec(2, seq($.if, '(', $.expression, ')', $.statement, $.else, $.statement))),
expressionStatement: $=> $.expression,
// Parser statements
parserStatements: $ => repeat1(seq($.parserStatement, $.semicolon)),
parserStatement: $ => choice($.conditionalStatement, $.parserBlockStatement, $.expressionStatement), // Limited, so far.
parserBlockStatement: $ => seq(optional($.annotations), '{', $.parserStatements, '}'),
parserTransitionStatement: $ => seq($.transition, $.transitionSelectionExpression),
// Expressions
expression: $ => choice($.identifier, $.integer, $.true, $.false), // Very limited.
selectExpression: $ => seq($.select, '(', $.expression, ')', '{', $.selectBody, '}'), // TODO: Should be expression list and not just a single expression
transitionSelectionExpression: $ => choice($.identifier, $.selectExpression),
keysetExpression: $ => $.expression,
// Tokens
semicolon: $ => ";",
colon: $ => ":",
todo: $ => "todo",
abstract: $ => "abstract",
action: $ => "action",
@@ -75,7 +100,7 @@ export default grammar({
match_kind: $ => "match_kind",
type: $ => "type",
out: $ => "out",
parser: $ => token.immediate("parser"),
parser: $ => "parser",
package: $ => "package",
pragma: $ => "pragma",
return: $ => "return",
@@ -92,13 +117,11 @@ export default grammar({
varbit: $ => "varbit",
valueset: $ => "valueset",
void: $ => "void",
identifier: $ => /[a-z]+/,
type_identifier: $ => token.immediate(/[a-z]+/),
identifier: $ => /[a-z_]+/,
type_identifier: $ => /[a-z]+/,
string_literal: $ => /".*"/,
integer: $ => /[0-9]+/,
// Very limited.
expression: $ => choice($.integer, $.true),
},
}
);