refactor(ast): use atom for Directive and Hashbang (#701)

The main reason is using Atom to remove the lifetime for convenience.

And after removing the lifetime of these nodes, the `Program<'a>`
doesn't rely on `&'a source` anymore, which allows us to [specify more
accurate
lifetimes](https://github.com/web-infra-dev/oxc/discussions/700).

crates/oxc_ast/src/ast/js.rs

@@ -17,8 +17,8 @@ pub struct Program<'a> {
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
     pub source_type: SourceType,
-    pub directives: Vec<'a, Directive<'a>>,
+    pub directives: Vec<'a, Directive>,
-    pub hashbang: Option<Hashbang<'a>>,
+    pub hashbang: Option<Hashbang>,
     pub body: Vec<'a, Statement<'a>>,
 }
 
@@ -918,21 +918,21 @@ pub enum Statement<'a> {
 /// Directive Prologue
 #[derive(Debug, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize), serde(tag = "type"))]
-pub struct Directive<'a> {
+pub struct Directive {
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
     pub expression: StringLiteral,
     // directives should always use the unescaped raw string
-    pub directive: &'a str,
+    pub directive: Atom,
 }
 
 /// Hashbang
 #[derive(Debug, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize), serde(tag = "type"))]
-pub struct Hashbang<'a> {
+pub struct Hashbang {
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
-    pub value: &'a str,
+    pub value: Atom,
 }
 
 /// Block Statement
@@ -1447,7 +1447,7 @@ impl<'a> FormalParameters<'a> {
 pub struct FunctionBody<'a> {
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
-    pub directives: Vec<'a, Directive<'a>>,
+    pub directives: Vec<'a, Directive>,
     pub statements: Vec<'a, Statement<'a>>,
 }
 

crates/oxc_ast/src/ast_builder.rs

@@ -59,7 +59,7 @@ impl<'a> AstBuilder<'a> {
         span: Span,
         source_type: SourceType,
         directives: Vec<'a, Directive>,
-        hashbang: Option<Hashbang<'a>>,
+        hashbang: Option<Hashbang>,
         body: Vec<'a, Statement<'a>>,
     ) -> Program<'a> {
         Program { span, source_type, directives, hashbang, body }
@@ -109,16 +109,11 @@ impl<'a> AstBuilder<'a> {
 
     /* ---------- Statements ---------- */
 
-    pub fn directive(
+    pub fn directive(&self, span: Span, expression: StringLiteral, directive: Atom) -> Directive {
-        &self,
-        span: Span,
-        expression: StringLiteral,
-        directive: &'a str,
-    ) -> Directive<'a> {
         Directive { span, expression, directive }
     }
 
-    pub fn hashbang(&self, span: Span, value: &'a str) -> Hashbang<'a> {
+    pub fn hashbang(&self, span: Span, value: Atom) -> Hashbang {
         Hashbang { span, value }
     }
 

crates/oxc_ast/src/ast_kind.rs

@@ -7,8 +7,8 @@ use crate::ast::*;
 #[derive(Debug, Clone, Copy)]
 pub enum AstKind<'a> {
     Program(&'a Program<'a>),
-    Directive(&'a Directive<'a>),
+    Directive(&'a Directive),
-    Hashbang(&'a Hashbang<'a>),
+    Hashbang(&'a Hashbang),
 
     BlockStatement(&'a BlockStatement<'a>),
     BreakStatement(&'a BreakStatement),
@@ -387,7 +387,7 @@ impl<'a> AstKind<'a> {
     pub fn debug_name(&self) -> std::borrow::Cow<str> {
         match self {
             Self::Program(_) => "Program".into(),
-            Self::Directive(d) => d.directive.into(),
+            Self::Directive(d) => d.directive.as_ref().into(),
             Self::Hashbang(_) => "Hashbang".into(),
 
             Self::BlockStatement(_) => "BlockStatement".into(),

crates/oxc_ast/src/visit.rs

@@ -271,7 +271,7 @@ pub trait Visit<'a>: Sized {
         self.leave_node(kind);
     }
 
-    fn visit_directive(&mut self, directive: &'a Directive<'a>) {
+    fn visit_directive(&mut self, directive: &'a Directive) {
         let kind = AstKind::Directive(directive);
         self.enter_node(kind);
         self.visit_string_literal(&directive.expression);

crates/oxc_ast/src/visit_mut.rs

@@ -193,7 +193,7 @@ pub trait VisitMut<'a, 'b>: Sized {
         self.visit_statement(&mut stmt.body);
     }
 
-    fn visit_directive(&mut self, directive: &'b mut Directive<'a>) {
+    fn visit_directive(&mut self, directive: &'b mut Directive) {
         self.visit_string_literal(&mut directive.expression);
     }
 

crates/oxc_ast_lower/src/lib.rs

@@ -160,13 +160,13 @@ impl<'a> AstLower<'a> {
         self.hir.program(program.span, directives, hashbang, statements)
     }
 
-    fn lower_hasbang(&mut self, hashbang: &ast::Hashbang<'a>) -> hir::Hashbang<'a> {
+    fn lower_hasbang(&mut self, hashbang: &ast::Hashbang) -> hir::Hashbang {
-        self.hir.hashbang(hashbang.span, hashbang.value)
+        self.hir.hashbang(hashbang.span, hashbang.value.clone())
     }
 
-    fn lower_directive(&mut self, directive: &ast::Directive<'a>) -> hir::Directive<'a> {
+    fn lower_directive(&mut self, directive: &ast::Directive) -> hir::Directive {
         let expression = self.lower_string_literal(&directive.expression);
-        self.hir.directive(directive.span, expression, directive.directive)
+        self.hir.directive(directive.span, expression, directive.directive.clone())
     }
 
     fn lower_statement(&mut self, statement: &ast::Statement<'a>) -> Option<hir::Statement<'a>> {

crates/oxc_formatter/src/gen.rs

@@ -30,7 +30,7 @@ impl<'a> Gen for Program<'a> {
     }
 }
 
-impl<'a> Gen for Directive<'a> {
+impl Gen for Directive {
     fn gen(&self, p: &mut Formatter) {
         p.print_indent();
         p.print(b'"');

crates/oxc_hir/src/hir.rs

@@ -25,8 +25,8 @@ use crate::HirId;
 pub struct Program<'a> {
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
-    pub directives: Vec<'a, Directive<'a>>,
+    pub directives: Vec<'a, Directive>,
-    pub hashbang: Option<Hashbang<'a>>,
+    pub hashbang: Option<Hashbang>,
     pub body: Vec<'a, Statement<'a>>,
 }
 
@@ -1039,25 +1039,25 @@ pub enum Statement<'a> {
 /// Directive Prologue
 #[derive(Debug, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize), serde(tag = "type"))]
-pub struct Directive<'a> {
+pub struct Directive {
     #[cfg_attr(feature = "serde", serde(skip))]
     pub hir_id: HirId,
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
     pub expression: StringLiteral,
     // directives should always use the unescaped raw string
-    pub directive: &'a str,
+    pub directive: Atom,
 }
 
 /// Hashbang
 #[derive(Debug, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize), serde(tag = "type"))]
-pub struct Hashbang<'a> {
+pub struct Hashbang {
     #[cfg_attr(feature = "serde", serde(skip))]
     pub hir_id: HirId,
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
-    pub value: &'a str,
+    pub value: Atom,
 }
 
 /// Block Statement
@@ -1501,7 +1501,7 @@ impl<'a> FormalParameters<'a> {
 pub struct FunctionBody<'a> {
     #[cfg_attr(feature = "serde", serde(flatten))]
     pub span: Span,
-    pub directives: Vec<'a, Directive<'a>>,
+    pub directives: Vec<'a, Directive>,
     pub statements: Vec<'a, Statement<'a>>,
 }
 

crates/oxc_hir/src/hir_builder.rs

@@ -66,7 +66,7 @@ impl<'a> HirBuilder<'a> {
         &mut self,
         span: Span,
         directives: Vec<'a, Directive>,
-        hashbang: Option<Hashbang<'a>>,
+        hashbang: Option<Hashbang>,
         body: Vec<'a, Statement<'a>>,
     ) -> Program<'a> {
         Program { span, directives, hashbang, body }
@@ -209,12 +209,12 @@ impl<'a> HirBuilder<'a> {
         &mut self,
         span: Span,
         expression: StringLiteral,
-        directive: &'a str,
+        directive: Atom,
-    ) -> Directive<'a> {
+    ) -> Directive {
         Directive { hir_id: self.next_id(), span, expression, directive }
     }
 
-    pub fn hashbang(&mut self, span: Span, value: &'a str) -> Hashbang<'a> {
+    pub fn hashbang(&mut self, span: Span, value: Atom) -> Hashbang {
         Hashbang { hir_id: self.next_id(), span, value }
     }
 

crates/oxc_hir/src/hir_kind.rs

@@ -9,7 +9,7 @@ pub enum HirKind<'a> {
     Root,
 
     Program(&'a Program<'a>),
-    Directive(&'a Directive<'a>),
+    Directive(&'a Directive),
 
     BlockStatement(&'a BlockStatement<'a>),
     BreakStatement(&'a BreakStatement),

crates/oxc_hir/src/visit.rs

@@ -313,7 +313,7 @@ pub trait Visit<'a>: Sized {
         self.leave_node(kind);
     }
 
-    fn visit_directive(&mut self, directive: &'a Directive<'a>) {
+    fn visit_directive(&mut self, directive: &'a Directive) {
         let kind = HirKind::Directive(directive);
         self.enter_node(kind);
         self.visit_string_literal(&directive.expression);

crates/oxc_hir/src/visit_mut.rs

@@ -206,7 +206,7 @@ pub trait VisitMut<'a, 'b>: Sized {
         }
     }
 
-    fn visit_directive(&mut self, directive: &'b mut Directive<'a>) {
+    fn visit_directive(&mut self, directive: &'b mut Directive) {
         self.visit_string_literal(&mut directive.expression);
     }
 

crates/oxc_minifier/src/printer/gen.rs

@@ -53,14 +53,14 @@ impl<'a> Gen for Program<'a> {
     }
 }
 
-impl<'a> Gen for Hashbang<'a> {
+impl Gen for Hashbang {
     fn gen(&self, p: &mut Printer, ctx: Context) {
         p.print_str(b"#!");
         p.print_str(self.value.as_bytes());
     }
 }
 
-impl<'a> Gen for Directive<'a> {
+impl Gen for Directive {
     fn gen(&self, p: &mut Printer, ctx: Context) {
         p.print(b'"');
         p.print_str(self.directive.as_bytes());

crates/oxc_parser/src/js/statement.rs

@@ -1,7 +1,7 @@
 use oxc_allocator::{Box, Vec};
 use oxc_ast::ast::*;
 use oxc_diagnostics::Result;
-use oxc_span::Span;
+use oxc_span::{Atom, Span};
 
 use super::{
     declaration::{VariableDeclarationContext, VariableDeclarationParent},
@@ -14,13 +14,13 @@ impl<'a> Parser<'a> {
     // Section 12
     // The InputElementHashbangOrRegExp goal is used at the start of a Script
     // or Module.
-    pub(crate) fn parse_hashbang(&mut self) -> Option<Hashbang<'a>> {
+    pub(crate) fn parse_hashbang(&mut self) -> Option<Hashbang> {
         if self.cur_kind() == Kind::HashbangComment {
             let span = self.start_span();
             self.bump_any();
             let span = self.end_span(span);
             let src = &self.source_text[span.start as usize + 2..span.end as usize];
-            Some(self.ast.hashbang(span, src))
+            Some(self.ast.hashbang(span, Atom::from(src)))
         } else {
             None
         }
@@ -33,7 +33,7 @@ impl<'a> Parser<'a> {
     pub(crate) fn parse_directives_and_statements(
         &mut self,
         is_top_level: bool,
-    ) -> Result<(Vec<'a, Directive<'a>>, Vec<'a, Statement<'a>>)> {
+    ) -> Result<(Vec<'a, Directive>, Vec<'a, Statement<'a>>)> {
         let mut directives = self.ast.new_vec();
         let mut statements = self.ast.new_vec();
 
@@ -64,8 +64,11 @@ impl<'a> Parser<'a> {
                             if let Expression::StringLiteral(string) = &expr.expression {
                                 let src = &self.source_text
                                     [string.span.start as usize + 1..string.span.end as usize - 1];
-                                let directive =
+                                let directive = self.ast.directive(
-                                    self.ast.directive(expr.span, (*string).clone(), src);
+                                    expr.span,
+                                    (*string).clone(),
+                                    Atom::from(src),
+                                );
                                 directives.push(directive);
                                 continue;
                             }