Start making the CST usable in Lute

batteries/syntax/ast_types.luau

@@ -0,0 +1,141 @@
+export type Position = {
+	line: number,
+	column: number,
+}
+
+export type Location = {
+	begin: Position,
+	["end"]: Position, -- TODO: do we really want to have to use brackets everywhere?
+}
+
+export type Whitespace = {
+	tag: "whitespace",
+	location: Location,
+	text: string,
+}
+
+export type SingleLineComment = {
+	tag: "comment",
+	location: Location,
+	text: string,
+}
+
+export type MultiLineComment = {
+	tag: "blockcomment",
+	location: Location,
+	text: string,
+	-- TODO: depth: number,
+}
+
+export type Trivia = Whitespace | SingleLineComment | MultiLineComment
+
+export type Token<Kind = string> = {
+	read leadingTrivia: { Trivia },
+	read position: Position,
+	read text: Kind,
+	read trailingTrivia: { Trivia },
+}
+
+export type Pair<T, Separator> = { node: T, separator: Token<Separator>? }
+export type Punctuated<T, Separator = ","> = { Pair<T, Separator> }
+
+export type AstLocal = {
+	name: Token<string>,
+}
+
+export type AstExprConstantString = Token<string> & {
+	tag: "string",
+	quoteStyle: "single" | "double" | "block" | "interp",
+	blockDepth: number,
+}
+
+export type AstExprLocal = {
+	tag: "local",
+	token: Token<string>,
+	["local"]: AstLocal,
+	upvalue: boolean,
+}
+
+export type AstExprGlobal = {
+	tag: "global",
+	name: Token,
+}
+
+export type AstExprCall = {
+	tag: "call",
+	func: AstExpr, -- TODO: stricter?
+	openParens: Token<"(">?,
+	arguments: Punctuated<AstExpr>,
+	closeParens: Token<")">?,
+}
+
+export type AstExprIndexName = {
+	tag: "indexname",
+	expr: AstExpr,
+	accessor: Token<"." | ":">,
+	index: Token<string>,
+	indexLocation: Location,
+}
+
+export type AstExprIndexExpr = {
+	tag: "index",
+	expr: AstExpr,
+	index: AstExpr,
+}
+
+export type AstExprBinary = {
+	tag: "binary",
+	lhsoperand: AstExpr,
+	operator: Token, -- TODO: enforce token type
+	rhsoperand: AstExpr,
+}
+
+export type AstExprTableItem =
+	| { kind: "list", value: AstExpr }
+	| { kind: "record", key: string, equals: Token<"=">, value: AstExpr }
+	| { kind: "general", key: string, equals: Token<"=">, value: AstExpr }
+
+export type AstExprTable = {
+	tag: "table",
+	openBrace: Token<"{">,
+	entries: { never },
+	closeBrace: Token<"}">,
+}
+
+export type AstExpr =
+	| AstExprConstantString
+	| AstExprLocal
+	| AstExprGlobal
+	| AstExprCall
+	| AstExprIndexName
+	| AstExprIndexExpr
+	| AstExprBinary
+	| AstExprTable
+
+export type AstStatBlock = {
+	tag: "block",
+	statements: { AstStat },
+}
+
+export type AstStatReturn = {
+	tag: "return",
+	["return"]: Token<"return">,
+	expressions: Punctuated<AstExpr>,
+}
+
+export type AstStatExpr = {
+	tag: "expression",
+	expression: AstExpr,
+}
+
+export type AstStatLocal = {
+	tag: "local",
+	["local"]: Token<"local">,
+	variables: Punctuated<AstLocal>,
+	equals: Token<"=">?,
+	values: Punctuated<AstExpr>,
+}
+
+export type AstStat = AstStatBlock | AstStatReturn | AstStatExpr | AstStatLocal
+
+return {}

batteries/syntax/parser.luau

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+--!strict
+
+local luau = require("@lute/luau")
+local T = require("./ast_types")
+
+--- Parses Luau source code into an AstStatBlock
+local function parse(source: string): T.AstStatBlock
+	return luau.parse(source).root
+end
+
+return {
+	parse = parse,
+}

batteries/syntax/printer.luau

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+--!strict
+local T = require("./ast_types")
+local visitor = require("./visitor")
+
+local function exhaustiveMatch(value: never): never
+	error(`Unknown value in exhaustive match: {value}`)
+end
+
+local function printTrivia(trivia: T.Trivia): string
+	if trivia.tag == "whitespace" or trivia.tag == "comment" or trivia.tag == "blockcomment" then
+		return trivia.text
+	else
+		return exhaustiveMatch(trivia.tag)
+	end
+end
+
+local function printTriviaList(trivia: { T.Trivia })
+	local result = ""
+	for _, trivia in trivia do
+		result ..= printTrivia(trivia)
+	end
+	return result
+end
+
+local function printToken(token: T.Token): string
+	return printTriviaList(token.leadingTrivia) .. token.text .. printTriviaList(token.trailingTrivia)
+end
+
+local function printString(expr: T.AstExprConstantString): string
+	local result = printTriviaList(expr.leadingTrivia)
+
+	if expr.quoteStyle == "single" then
+		result ..= `'{expr.text}'`
+	elseif expr.quoteStyle == "double" then
+		result ..= `"{expr.text}"`
+	elseif expr.quoteStyle == "block" then
+		local equals = string.rep("=", expr.blockDepth)
+		result ..= `[{equals}[{expr.text}]{equals}]`
+	elseif expr.quoteStyle == "interp" then
+		result ..= "`" .. expr.text .. "`"
+	else
+		return exhaustiveMatch(expr.quoteStyle)
+	end
+
+	result ..= printTriviaList(expr.trailingTrivia)
+	return result
+end
+
+--- Returns a string representation of an AstStatBlock
+local function printBlock(block: T.AstStatBlock): string
+	local printer = visitor.createVisitor()
+	local result = ""
+
+	printer.visitToken = function(node: T.Token)
+		result ..= printToken(node)
+		return false
+	end
+
+	printer.visitString = function(node: T.AstExprConstantString)
+		result ..= printString(node)
+		return false
+	end
+
+	visitor.visitBlock(block, printer)
+
+	return result
+end
+
+return {
+	print = printBlock,
+}