func string_literal_expr(value: String, source_id: Int, source_span: Range<Int>, context: &QuoteContext) -> Syntax<Expr>Construct a category-checked string literal without routing generated text through the lexer. This is intentionally a literal-only constructor: macro authors still cannot manufacture identifiers or their syntax contexts from strings. The generated token points back to the source syntax that caused the literal so diagnostics retain useful provenance.
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pub func string_literal_expr(value: String, source_id: Int, source_span: Range<Int>, context: &QuoteContext) -> Syntax<Expr> {
let spelling_builder = StringBuilder(capacity: value.utf8_count() + 2)
spelling_builder.append(string: "\"")
for character in value {
spelling_builder.append(string: match character {
'\\' -> "\\\\",
'\"' -> "\\\"",
'\n' -> "\\n",
'\r' -> "\\r",
'\t' -> "\\t",
_ -> character.to_string()
})
}
spelling_builder.append(string: "\"")
let spelling = spelling_builder.finish()
let token = SyntaxToken(
kind: .string_literal,
leading: "",
spelling: spelling,
lexeme_start: 0,
lexeme_end: spelling.utf8().count(),
source_id: source_id,
source_span: source_span,
context: introduced_context(context: context),
origin: .definition_site
)
Syntax<Expr>(raw: RawSyntax(category: .expr, pieces: [.token(token)], trailing: "", group_when_spliced: true))
}