feat: count-vowels-kvstore plugin

Cargo.toml

@@ -4,6 +4,7 @@ members = [
 	"reflect",
 	"store_credit",
   "loop_forever",
+  "count_vowels_kvstore",
 ]
 resolver = "2"
 

count_vowels/src/lib.rs

@@ -51,4 +51,3 @@ pub unsafe fn count_vowels(input: String) -> FnResult<Json<VowelReport>> {
 
     Ok(Json(output))
 }
-

count_vowels_kvstore/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "count_vowels_kvstore"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow.workspace = true
+serde.workspace = true
+extism-pdk.workspace = true
+
+[lib]
+crate_type = ["cdylib"]

count_vowels_kvstore/src/lib.rs

@@ -0,0 +1,61 @@
+use anyhow::Result;
+use extism_pdk::*;
+use serde::Serialize;
+
+#[host_fn]
+extern "ExtismHost" {
+    fn kv_read(key: String) -> Vec<u8>;
+    fn kv_write(key: String, value: Vec<u8>);
+}
+
+const VOWELS: &str = "aeiouAEIOU";
+const KV_REPORT_KEY: &str = "count-vowels";
+
+#[derive(Serialize)]
+struct VowelReport {
+    pub count: u32,
+    pub total: u32,
+    pub vowels: String,
+}
+
+fn get_total() -> Result<u32> {
+    let v = unsafe { kv_read(KV_REPORT_KEY.into()) }?;
+    // assume it's the correct size
+    let array: [u8; 4] = [v[0], v[1], v[2], v[3]];
+    Ok(u32::from_le_bytes(array))
+}
+
+fn store_total(total: u32) -> Result<()> {
+    unsafe { kv_write(KV_REPORT_KEY.into(), total.to_le_bytes().into())? };
+    Ok(())
+}
+
+fn get_vowels() -> String {
+    match config::get("vowels") {
+        Some(v) => v,
+        None => VOWELS.to_string(),
+    }
+}
+
+#[plugin_fn]
+pub unsafe fn count_vowels(input: String) -> FnResult<Json<VowelReport>> {
+    let mut count = 0;
+    let vowels = get_vowels();
+    for ch in input.chars() {
+        if vowels.contains(ch) {
+            count += 1;
+        }
+    }
+
+    let mut total = get_total()?;
+    total += count;
+    store_total(total)?;
+
+    let output = VowelReport {
+        count,
+        total,
+        vowels,
+    };
+
+    Ok(Json(output))
+}