Rename Extract to VarName, since Extract is a built in type

Author: lisajian

spec/common/params.spec.ts

@@ -20,7 +20,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE ignoreUnusedWarning OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
-import { Extract, ParamsOf, Split } from "../../src/common/params";
+import { VarName, ParamsOf, Split } from "../../src/common/params";
 import { expectNever, expectType } from "./metaprogramming";
 
 describe("Params namespace", () => {
@@ -56,21 +56,21 @@ describe("Params namespace", () => {
     });
   });
 
-  describe("Extract", () => {
+  describe("VarName", () => {
     it("extracts nothing from strings without params", () => {
-      expectNever<Extract<"uid">>();
+      expectNever<VarName<"uid">>();
     });
 
     it("extracts {segment} captures", () => {
-      expectType<Extract<"{uid}">>("uid");
+      expectType<VarName<"{uid}">>("uid");
     });
 
     it("extracts {segment=*} captures", () => {
-      expectType<Extract<"{uid=*}">>("uid");
+      expectType<VarName<"{uid=*}">>("uid");
     });
 
     it("extracts {segment=**} captures", () => {
-      expectType<Extract<"{uid=**}">>("uid");
+      expectType<VarName<"{uid=**}">>("uid");
     });
   });
 

src/common/params.ts

@@ -60,11 +60,11 @@ export type NullSafe<S extends null | undefined | string> = S extends null
  * A type that extracts parameter name enclosed in bracket as string.
  * Ignore wildcard matches
  *
- * For example, Extract<"{uid}"> is "uid".
- * For example, Extract<"{uid=*}"> is "uid".
- * For example, Extract<"{uid=**}"> is "uid".
+ * For example, VarName<"{uid}"> is "uid".
+ * For example, VarName<"{uid=*}"> is "uid".
+ * For example, VarName<"{uid=**}"> is "uid".
  */
-export type Extract<Part extends string> = Part extends `{${infer Param}=**}`
+export type VarName<Part extends string> = Part extends `{${infer Param}=**}`
   ? Param
   : Part extends `{${infer Param}=*}`
   ? Param
@@ -90,7 +90,7 @@ export type ParamsOf<PathPattern extends string | Expression<string>> =
         // N.B. I'm not sure why PathPattern isn't detected to not be an
         // Expression<string> per the check above. Since we have the check above
         // The Exclude call should be safe.
-        [Key in Extract<
+        [Key in VarName<
           Split<NullSafe<Exclude<PathPattern, Expression<string>>>, "/">[number]
         >]: string;
       };