feat: add SWC dependency analyzer (#5015)

This commit adds "analyze_dependencies" function that uses SWC
(by the means of AstParser) to perform analysis of static and dynamic
imports.

1 files changed, 155 insertions, 0 deletions

diff --git a/cli/swc_util.rs b/cli/swc_util.rs
index 2086a5ded..a2e5d50fd 100644
--- a/cli/swc_util.rs
+++ b/cli/swc_util.rs
@@ -18,6 +18,8 @@ use crate::swc_ecma_parser::Session;
 use crate::swc_ecma_parser::SourceFileInput;
 use crate::swc_ecma_parser::Syntax;
 use crate::swc_ecma_parser::TsConfig;
+use swc_ecma_visit::Node;
+use swc_ecma_visit::Visit;
 
 use std::error::Error;
 use std::fmt;
@@ -162,3 +164,156 @@ impl AstParser {
       .unwrap_or_else(|| vec![])
   }
 }
+
+struct DependencyVisitor {
+  dependencies: Vec<String>,
+  analyze_dynamic_imports: bool,
+}
+
+impl Visit for DependencyVisitor {
+  fn visit_import_decl(
+    &mut self,
+    import_decl: &swc_ecma_ast::ImportDecl,
+    _parent: &dyn Node,
+  ) {
+    let src_str = import_decl.src.value.to_string();
+    self.dependencies.push(src_str);
+  }
+
+  fn visit_named_export(
+    &mut self,
+    named_export: &swc_ecma_ast::NamedExport,
+    _parent: &dyn Node,
+  ) {
+    if let Some(src) = &named_export.src {
+      let src_str = src.value.to_string();
+      self.dependencies.push(src_str);
+    }
+  }
+
+  fn visit_export_all(
+    &mut self,
+    export_all: &swc_ecma_ast::ExportAll,
+    _parent: &dyn Node,
+  ) {
+    let src_str = export_all.src.value.to_string();
+    self.dependencies.push(src_str);
+  }
+
+  fn visit_call_expr(
+    &mut self,
+    call_expr: &swc_ecma_ast::CallExpr,
+    _parent: &dyn Node,
+  ) {
+    if !self.analyze_dynamic_imports {
+      return;
+    }
+
+    use swc_ecma_ast::Expr::*;
+    use swc_ecma_ast::ExprOrSuper::*;
+
+    let boxed_expr = match call_expr.callee.clone() {
+      Super(_) => return,
+      Expr(boxed) => boxed,
+    };
+
+    match &*boxed_expr {
+      Ident(ident) => {
+        if &ident.sym.to_string() != "import" {
+          return;
+        }
+      }
+      _ => return,
+    };
+
+    if let Some(arg) = call_expr.args.get(0) {
+      match &*arg.expr {
+        Lit(lit) => {
+          if let swc_ecma_ast::Lit::Str(str_) = lit {
+            let src_str = str_.value.to_string();
+            self.dependencies.push(src_str);
+          }
+        }
+        _ => return,
+      }
+    }
+  }
+}
+
+/// Given file name and source code return vector
+/// of unresolved import specifiers.
+///
+/// Returned vector may contain duplicate entries.
+///
+/// Second argument allows to configure if dynamic
+/// imports should be analyzed.
+///
+/// NOTE: Only statically analyzable dynamic imports
+/// are considered; ie. the ones that have plain string specifier:
+///
+///    await import("./fizz.ts")
+///
+/// These imports will be ignored:
+///
+///    await import(`./${dir}/fizz.ts`)
+///    await import("./" + "fizz.ts")
+#[allow(unused)]
+pub fn analyze_dependencies(
+  source_code: &str,
+  analyze_dynamic_imports: bool,
+) -> Result<Vec<String>, SwcDiagnosticBuffer> {
+  let parser = AstParser::new();
+  parser.parse_module("root.ts", source_code, |parse_result| {
+    let module = parse_result?;
+    let mut collector = DependencyVisitor {
+      dependencies: vec![],
+      analyze_dynamic_imports,
+    };
+    collector.visit_module(&module, &module);
+    Ok(collector.dependencies)
+  })
+}
+
+#[test]
+fn test_analyze_dependencies() {
+  let source = r#"
+import { foo } from "./foo.ts";
+export { bar } from "./foo.ts";
+export * from "./bar.ts";
+"#;
+
+  let dependencies =
+    analyze_dependencies(source, false).expect("Failed to parse");
+  assert_eq!(
+    dependencies,
+    vec![
+      "./foo.ts".to_string(),
+      "./foo.ts".to_string(),
+      "./bar.ts".to_string(),
+    ]
+  );
+}
+
+#[test]
+fn test_analyze_dependencies_dyn_imports() {
+  let source = r#"
+import { foo } from "./foo.ts";
+export { bar } from "./foo.ts";
+export * from "./bar.ts";
+
+const a = await import("./fizz.ts");
+const a = await import("./" + "buzz.ts");
+"#;
+
+  let dependencies =
+    analyze_dependencies(source, true).expect("Failed to parse");
+  assert_eq!(
+    dependencies,
+    vec![
+      "./foo.ts".to_string(),
+      "./foo.ts".to_string(),
+      "./bar.ts".to_string(),
+      "./fizz.ts".to_string(),
+    ]
+  );
+}