feat(strings): add interpolateKeys()

thi-ng · Jan 4, 2021 · bd78d1d · bd78d1d
1 parent fb4470d
commit bd78d1d
Show file tree

Hide file tree

Showing 2 changed files with 29 additions and 1 deletion.
diff --git a/packages/strings/package.json b/packages/strings/package.json
@@ -68,6 +68,7 @@
         "functional",
         "hex",
         "higher-order",
+        "interpolation",
         "number",
         "padding",
         "percent",

diff --git a/packages/strings/src/interpolate.ts b/packages/strings/src/interpolate.ts
@@ -1,4 +1,8 @@
+import type { IObjectOf, NumOrString } from "@thi.ng/api";
+import { illegalArgs } from "@thi.ng/errors";
+
 const TPL = /\{(\d+)\}/g;
+const TPL_K = /\{([a-z0-9_.-]+)\}/gi;
 
 /**
  * Takes a string template with embedded `{number}` style terms and any
@@ -16,5 +20,28 @@ const TPL = /\{(\d+)\}/g;
  */
 export const interpolate = (src: string, ...args: any[]) =>
     args.length > 0
-        ? src.replace(TPL, (m) => String(args[parseInt(m[1], 10)]))
+        ? src.replace(TPL, (_, id) => String(args[parseInt(id, 10)]))
         : src;
+
+/**
+ * Similar to {@link interpolate}, but uses alphanumeric placeholders in the
+ * template string and an object of values for the stated keys.
+ *
+ * @example
+ * ```ts
+ * interpolateKeys(
+ *   "let {id}: {type} = {val};",
+ *   { id: "a", type: "number", val: 42 }
+ * )
+ * // "let a: number = 42;"
+ * ```
+ *
+ * @param src
+ * @param keys
+ */
+export const interpolateKeys = (src: string, keys: IObjectOf<NumOrString>) =>
+    src.replace(TPL_K, (_, id) =>
+        keys[id] != undefined
+            ? String(keys[id])
+            : illegalArgs(`missing key: ${id}`)
+    );