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lib.rs
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lib.rs
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//! Oxc Codegen
//!
//! Supports
//!
//! * whitespace removal
//! * sourcemaps
//!
//! Code adapted from
//! * [esbuild](https://github.com/evanw/esbuild/blob/main/internal/js_printer/js_printer.go)
mod context;
mod gen;
mod gen_ts;
mod operator;
mod sourcemap_builder;
mod sourcemap_visualizer;
use std::str::from_utf8_unchecked;
#[allow(clippy::wildcard_imports)]
use oxc_ast::ast::*;
use oxc_span::{Atom, Span};
use oxc_syntax::{
identifier::is_identifier_part,
operator::{BinaryOperator, UnaryOperator, UpdateOperator},
precedence::Precedence,
symbol::SymbolId,
};
use sourcemap_builder::SourcemapBuilder;
pub use crate::{
context::Context,
gen::{Gen, GenExpr},
operator::Operator,
sourcemap_visualizer::SourcemapVisualizer,
};
// use crate::mangler::Mangler;
#[derive(Debug, Default, Clone)]
pub struct CodegenOptions {
/// Pass in the filename to enable source map support.
pub enable_source_map: bool,
/// Enable TypeScript code generation.
pub enable_typescript: bool,
}
pub struct CodegenReturn {
pub source_text: String,
pub source_map: Option<sourcemap::SourceMap>,
}
pub struct Codegen<const MINIFY: bool> {
#[allow(unused)]
options: CodegenOptions,
// mangler: Option<Mangler>,
/// Output Code
code: Vec<u8>,
// states
prev_op_end: usize,
prev_reg_exp_end: usize,
need_space_before_dot: usize,
/// For avoiding `;` if the previous statement ends with `}`.
needs_semicolon: bool,
prev_op: Option<Operator>,
start_of_stmt: usize,
start_of_arrow_expr: usize,
start_of_default_export: usize,
/// Track the current indentation level
indentation: u8,
sourcemap_builder: SourcemapBuilder,
}
#[derive(Debug, Clone, Copy)]
pub enum Separator {
Comma,
Semicolon,
None,
}
impl<const MINIFY: bool> Codegen<MINIFY> {
pub fn new(source_name: &str, source_text: &str, options: CodegenOptions) -> Self {
// Initialize the output code buffer to reduce memory reallocation.
// Minification will reduce by at least half of the original size.
let source_len = source_text.len();
let capacity = if MINIFY { source_len / 2 } else { source_len };
let mut sourcemap_builder = SourcemapBuilder::default();
if options.enable_source_map {
sourcemap_builder.with_name_and_source(source_name, source_text);
}
Self {
options,
// mangler: None,
code: Vec::with_capacity(capacity),
needs_semicolon: false,
need_space_before_dot: 0,
prev_op_end: 0,
prev_reg_exp_end: 0,
prev_op: None,
start_of_stmt: 0,
start_of_arrow_expr: 0,
start_of_default_export: 0,
indentation: 0,
sourcemap_builder,
}
}
// fn with_mangler(&mut self, mangler: Mangler) {
// self.mangler = Some(mangler);
// }
pub fn build(mut self, program: &Program<'_>) -> CodegenReturn {
program.gen(&mut self, Context::default());
let source_text = self.into_source_text();
let source_map = self.sourcemap_builder.into_sourcemap();
CodegenReturn { source_text, source_map }
}
pub fn into_source_text(&mut self) -> String {
// SAFETY: criteria of `from_utf8_unchecked` are met.
unsafe { String::from_utf8_unchecked(std::mem::take(&mut self.code)) }
}
fn code(&self) -> &Vec<u8> {
&self.code
}
fn code_len(&self) -> usize {
self.code().len()
}
/// Push a single character into the buffer
pub fn print(&mut self, ch: u8) {
self.code.push(ch);
}
/// Push a string into the buffer
pub fn print_str(&mut self, s: &[u8]) {
self.code.extend_from_slice(s);
}
fn print_soft_space(&mut self) {
if !MINIFY {
self.print(b' ');
}
}
pub fn print_hard_space(&mut self) {
self.print(b' ');
}
fn print_soft_newline(&mut self) {
if !MINIFY {
self.print(b'\n');
}
}
fn print_semicolon(&mut self) {
self.print(b';');
}
fn print_comma(&mut self) {
self.print(b',');
}
fn print_space_before_identifier(&mut self) {
if self
.peek_nth(0)
.is_some_and(|ch| is_identifier_part(ch) || self.prev_reg_exp_end == self.code.len())
{
self.print_hard_space();
}
}
fn peek_nth(&self, n: usize) -> Option<char> {
// SAFETY: criteria of `from_utf8_unchecked` are met.
unsafe { from_utf8_unchecked(self.code()) }.chars().nth_back(n)
}
fn indent(&mut self) {
if !MINIFY {
self.indentation += 1;
}
}
fn dedent(&mut self) {
if !MINIFY {
self.indentation -= 1;
}
}
fn print_indent(&mut self) {
if !MINIFY {
for _ in 0..self.indentation {
self.print(b'\t');
}
}
}
fn print_semicolon_after_statement(&mut self) {
if MINIFY {
self.needs_semicolon = true;
} else {
self.print_str(b";\n");
}
}
fn print_semicolon_if_needed(&mut self) {
if self.needs_semicolon {
self.print_semicolon();
self.needs_semicolon = false;
}
}
fn print_ellipsis(&mut self) {
self.print_str(b"...");
}
pub fn print_colon(&mut self) {
self.print(b':');
}
fn print_equal(&mut self) {
self.print(b'=');
}
fn print_sequence<T: Gen<MINIFY>>(&mut self, items: &[T], separator: Separator, ctx: Context) {
let len = items.len();
for (index, item) in items.iter().enumerate() {
item.gen(self, ctx);
match separator {
Separator::Semicolon => self.print_semicolon(),
Separator::Comma => self.print(b','),
Separator::None => {}
}
if index != len - 1 {}
}
}
fn print_block_start(&mut self, position: u32) {
self.add_source_mapping(position);
self.print(b'{');
self.print_soft_newline();
self.indent();
}
fn print_block_end(&mut self, position: u32) {
self.dedent();
self.print_indent();
self.add_source_mapping(position);
self.print(b'}');
}
fn print_block1(&mut self, stmt: &BlockStatement<'_>, ctx: Context) {
self.print_block_start(stmt.span.start);
self.print_directives_and_statements_with_semicolon_order(None, &stmt.body, ctx, true);
self.print_block_end(stmt.span.end);
self.needs_semicolon = false;
}
fn print_block<T: Gen<MINIFY>>(
&mut self,
items: &[T],
separator: Separator,
ctx: Context,
span: Span,
) {
self.print_block_start(span.start);
self.print_sequence(items, separator, ctx);
self.print_block_end(span.end);
}
fn print_list<T: Gen<MINIFY>>(&mut self, items: &[T], ctx: Context) {
for (index, item) in items.iter().enumerate() {
if index != 0 {
self.print_comma();
self.print_soft_space();
}
item.gen(self, ctx);
}
}
pub fn print_expression(&mut self, expr: &Expression<'_>) {
expr.gen_expr(self, Precedence::lowest(), Context::default());
}
fn print_expressions<T: GenExpr<MINIFY>>(
&mut self,
items: &[T],
precedence: Precedence,
ctx: Context,
) {
for (index, item) in items.iter().enumerate() {
if index != 0 {
self.print_comma();
}
item.gen_expr(self, precedence, ctx);
}
}
fn print_symbol(&mut self, start: u32, _symbol_id: Option<SymbolId>, fallback: &Atom) {
// if let Some(mangler) = &self.mangler {
// if let Some(symbol_id) = symbol_id {
// let name = mangler.get_symbol_name(symbol_id);
// self.print_str(name.clone().as_bytes());
// return;
// }
// }
self.add_source_mapping_for_name(start, fallback);
self.print_str(fallback.as_bytes());
}
fn print_space_before_operator(&mut self, next: Operator) {
if !MINIFY {
self.print_hard_space();
return;
}
if self.prev_op_end != self.code.len() {
return;
}
let Some(prev) = self.prev_op else { return };
// "+ + y" => "+ +y"
// "+ ++ y" => "+ ++y"
// "x + + y" => "x+ +y"
// "x ++ + y" => "x+++y"
// "x + ++ y" => "x+ ++y"
// "-- >" => "-- >"
// "< ! --" => "<! --"
let bin_op_add = Operator::Binary(BinaryOperator::Addition);
let bin_op_sub = Operator::Binary(BinaryOperator::Subtraction);
let un_op_pos = Operator::Unary(UnaryOperator::UnaryPlus);
let un_op_pre_inc = Operator::Update(UpdateOperator::Increment);
let un_op_neg = Operator::Unary(UnaryOperator::UnaryNegation);
let un_op_pre_dec = Operator::Update(UpdateOperator::Decrement);
let un_op_post_dec = Operator::Update(UpdateOperator::Decrement);
let bin_op_gt = Operator::Binary(BinaryOperator::GreaterThan);
let un_op_not = Operator::Unary(UnaryOperator::LogicalNot);
if ((prev == bin_op_add || prev == un_op_pos)
&& (next == bin_op_add || next == un_op_pos || next == un_op_pre_inc))
|| ((prev == bin_op_sub || prev == un_op_neg)
&& (next == bin_op_sub || next == un_op_neg || next == un_op_pre_dec))
|| (prev == un_op_post_dec && next == bin_op_gt)
|| (prev == un_op_not && next == un_op_pre_dec && self.peek_nth(1) == Some('<'))
{
self.print_hard_space();
}
}
fn wrap<F: FnMut(&mut Self)>(&mut self, wrap: bool, mut f: F) {
if wrap {
self.print(b'(');
}
f(self);
if wrap {
self.print(b')');
}
}
fn wrap_quote<F: FnMut(&mut Self, char)>(&mut self, s: &str, mut f: F) {
let quote = choose_quote(s);
self.print(quote as u8);
f(self, quote);
self.print(quote as u8);
}
fn print_directives_and_statements_with_semicolon_order(
&mut self,
directives: Option<&[Directive]>,
statements: &[Statement<'_>],
ctx: Context,
print_semicolon_first: bool,
) {
if let Some(directives) = directives {
if directives.is_empty() {
if let Some(Statement::ExpressionStatement(s)) = statements.first() {
if matches!(s.expression.get_inner_expression(), Expression::StringLiteral(_)) {
self.print_semicolon();
}
}
} else {
for directive in directives {
directive.gen(self, ctx);
}
self.print_soft_newline();
}
}
for stmt in statements {
if let Statement::Declaration(decl) = stmt {
if decl.is_typescript_syntax()
&& !self.options.enable_typescript
&& !matches!(decl, Declaration::TSEnumDeclaration(_))
{
continue;
}
}
if print_semicolon_first {
self.print_semicolon_if_needed();
stmt.gen(self, ctx);
} else {
stmt.gen(self, ctx);
self.print_semicolon_if_needed();
}
}
}
fn add_source_mapping(&mut self, position: u32) {
self.sourcemap_builder.add_source_mapping(&self.code, position, None);
}
fn add_source_mapping_for_name(&mut self, position: u32, name: &str) {
self.sourcemap_builder.add_source_mapping(&self.code, position, Some(name));
}
}
fn choose_quote(s: &str) -> char {
let mut single_cost = 0;
let mut double_cost = 0;
for c in s.chars() {
match c {
'\'' => single_cost += 1,
'"' => double_cost += 1,
_ => {}
}
}
if single_cost > double_cost {
'"'
} else {
'\''
}
}