feat(transfrom): transform-json-strings (#2168)

The pr intends to implement the plugin
`babel-plugin-transform-json-strings`. But here is only mutate
`Directive`, the `StringLiteral` is not implement. It need to changed
the `StringLiteral` printer.

I'm intend to add the raw of `StringLiteral`, it will be mutate at
plugin, and using the `raw` to print `StringLiteral`. If you other
ideas, please let me know.

---------

Co-authored-by: Boshen <boshenc@gmail.com>

crates/oxc_linter/Cargo.toml

@@ -46,9 +46,9 @@ language-tags = { workspace = true }
 mime_guess    = { workspace = true }
 url           = { workspace = true }
 
-rust-lapper = "1.1.0"
-once_cell   = "1.19.0"
-memchr      = "2.7.1"
+rust-lapper         = "1.1.0"
+once_cell           = "1.19.0"
+memchr              = "2.7.1"
 json-strip-comments = "1.0.1"
 
 [dev-dependencies]

crates/oxc_transformer/src/es2019/json_strings.rs

@@ -0,0 +1,56 @@
+use oxc_ast::ast::*;
+use oxc_span::Atom;
+use oxc_syntax::identifier::{LS, PS};
+
+use crate::options::{TransformOptions, TransformTarget};
+
+/// ES2019: Json Strings
+///
+/// References:
+/// * <https://babeljs.io/docs/babel-plugin-transform-json-strings>
+/// * <https://github.com/babel/babel/tree/main/packages/babel-plugin-transform-json-strings>
+pub struct JsonStrings;
+
+impl JsonStrings {
+    pub fn new(options: &TransformOptions) -> Option<Self> {
+        (options.target < TransformTarget::ES2019 || options.json_strings).then(|| Self {})
+    }
+
+    // Allow `U+2028` and `U+2029` in string literals
+    // <https://tc39.es/proposal-json-superset>
+    // <https://github.com/tc39/proposal-json-superset>
+    fn normalize_str(str: &str) -> Option<Atom> {
+        if !str.contains(LS) && !str.contains(PS) {
+            return None;
+        }
+        let mut buf = String::new();
+        let mut is_escaped = false;
+        for c in str.chars() {
+            match (is_escaped, c) {
+                (false, LS) => buf.push_str("\\u2028"),
+                (false, PS) => buf.push_str("\\u2029"),
+                _ => buf.push(c),
+            }
+            is_escaped = !is_escaped && matches!(c, '\\');
+        }
+        Some(buf.into())
+    }
+
+    #[allow(clippy::unused_self)]
+    // TODO oxc_codegen currently prints json strings correctly,
+    // but we need a way to turn off this behaviour from codegen
+    // and do the transformation here.
+    pub fn transform_string_literal(&mut self, _literal: &mut StringLiteral) {
+        // let str = &self.ctx.semantic().source_text()[literal.span.start as usize + 1..literal.span.end as usize - 1];
+        // if let Some(value) = Self::normalize_str(str) {
+        //     literal.value = value;
+        // }
+    }
+
+    #[allow(clippy::unused_self)]
+    pub fn transform_directive(&mut self, directive: &mut Directive) {
+        if let Some(value) = Self::normalize_str(directive.directive.as_str()) {
+            directive.directive = value;
+        }
+    }
+}

crates/oxc_transformer/src/es2019/mod.rs

@@ -1,3 +1,4 @@
+mod json_strings;
 mod optional_catch_binding;
-
+pub use json_strings::JsonStrings;
 pub use optional_catch_binding::OptionalCatchBinding;

crates/oxc_transformer/src/lib.rs

@@ -35,10 +35,18 @@ use oxc_span::SourceType;
 use proposals::Decorators;
 
 use crate::{
-    context::TransformerCtx, es2015::*, es2016::ExponentiationOperator,
-    es2019::OptionalCatchBinding, es2020::NullishCoalescingOperator,
-    es2021::LogicalAssignmentOperators, es2022::ClassStaticBlock, es3::PropertyLiteral,
-    react_jsx::ReactJsx, regexp::RegexpFlags, typescript::TypeScript, utils::CreateVars,
+    context::TransformerCtx,
+    es2015::*,
+    es2016::ExponentiationOperator,
+    es2019::{JsonStrings, OptionalCatchBinding},
+    es2020::NullishCoalescingOperator,
+    es2021::LogicalAssignmentOperators,
+    es2022::ClassStaticBlock,
+    es3::PropertyLiteral,
+    react_jsx::ReactJsx,
+    regexp::RegexpFlags,
+    typescript::TypeScript,
+    utils::CreateVars,
 };
 
 pub use crate::{
@@ -64,6 +72,7 @@ pub struct Transformer<'a> {
     // es2020
     es2020_nullish_coalescing_operators: Option<NullishCoalescingOperator<'a>>,
     // es2019
+    es2019_json_strings: Option<JsonStrings>,
     es2019_optional_catch_binding: Option<OptionalCatchBinding<'a>>,
     // es2016
     es2016_exponentiation_operator: Option<ExponentiationOperator<'a>>,
@@ -105,6 +114,7 @@ impl<'a> Transformer<'a> {
             // es2020
             es2020_nullish_coalescing_operators: NullishCoalescingOperator::new(Rc::clone(&ast), ctx.clone(), &options),
             // es2019
+            es2019_json_strings: JsonStrings::new(&options),
             es2019_optional_catch_binding: OptionalCatchBinding::new(Rc::clone(&ast), &options),
             // es2016
             es2016_exponentiation_operator: ExponentiationOperator::new(Rc::clone(&ast), ctx.clone(), &options),
@@ -291,4 +301,16 @@ impl<'a> VisitMut<'a> for Transformer<'a> {
 
         self.leave_node(kind);
     }
+
+    fn visit_directive(&mut self, directive: &mut Directive) {
+        self.es2019_json_strings
+            .as_mut()
+            .map(|t: &mut JsonStrings| t.transform_directive(directive));
+    }
+
+    fn visit_string_literal(&mut self, lit: &mut StringLiteral) {
+        self.es2019_json_strings
+            .as_mut()
+            .map(|t: &mut JsonStrings| t.transform_string_literal(lit));
+    }
 }

crates/oxc_transformer/src/options.rs

@@ -22,6 +22,7 @@ pub struct TransformOptions {
     pub nullish_coalescing_operator: Option<NullishCoalescingOperatorOptions>,
     // es2019
     pub optional_catch_binding: bool,
+    pub json_strings: bool,
     // es2016
     pub exponentiation_operator: bool,
     // es2015

tasks/transform_conformance/babel.snap.md

@@ -1,8 +1,9 @@
-Passed: 327/1369
+Passed: 329/1369
 
 # All Passed:
 * babel-plugin-transform-numeric-separator
 * babel-plugin-transform-optional-catch-binding
+* babel-plugin-transform-json-strings
 * babel-plugin-transform-shorthand-properties
 * babel-plugin-transform-sticky-regex
 * babel-plugin-transform-instanceof
@@ -607,10 +608,6 @@ Passed: 327/1369
 * transparent-expr-wrappers/ts-as-member-expression/input.ts
 * transparent-expr-wrappers/ts-parenthesized-expression-member-call/input.ts
 
-# babel-plugin-transform-json-strings (2/4)
-* json-strings/directive-line-separator/input.js
-* json-strings/directive-paragraph-separator/input.js
-
 # babel-plugin-transform-async-generator-functions (0/22)
 * async-generators/class-method/input.js
 * async-generators/class-private-method/input.js

tasks/transform_conformance/src/test_case.rs

@@ -111,6 +111,7 @@ pub trait TestCase {
             nullish_coalescing_operator: options
                 .get_plugin("transform-nullish-coalescing-operator")
                 .map(get_options::<NullishCoalescingOperatorOptions>),
+            json_strings: options.get_plugin("transform-json-strings").is_some(),
             optional_catch_binding: options
                 .get_plugin("transform-optional-catch-binding")
                 .is_some(),