Merge pull request #1 from ngortheone/example_simple

Add simple example from the readme (thanks to @ngortheone )

examples/simple.rs

@@ -0,0 +1,143 @@
+use melda::{filesystemadapter::FilesystemAdapter, melda::Melda};
+use serde_json::json;
+use std::fs;
+use std::io;
+use std::path::Path;
+use std::sync::{Arc, RwLock};
+
+fn main() {
+    // ensure clean state
+    _ = std::fs::remove_dir_all("todolist_alice");
+    _ = std::fs::remove_dir_all("todolist_bob");
+
+    // create alice storage adapter
+    let adapter_alice =
+        Box::new(FilesystemAdapter::new("todolist_alice").expect("Cannot initialize adapter"));
+
+    // initialize CRDT data structure
+    let melda_alice =
+        Melda::new(Arc::new(RwLock::new(adapter_alice))).expect("Failed to inizialize Melda");
+
+    // create new JSON object
+    let v = json!({ "software" : "MeldaDo", "version" : "1.0.0", "items♭" : []})
+        .as_object()
+        .expect("Not an object")
+        .clone();
+
+    // update CRDT with new json
+    melda_alice.update(v).expect("Failed to update");
+
+    // commit change
+    let info = json!({ "author" : "Alice", "description" : "First commit" })
+        .as_object()
+        .expect("Not an object")
+        .clone();
+    let commit_result = melda_alice.commit(Some(info)).unwrap().unwrap();
+    println!("alice made a commit: {}", commit_result);
+
+    // create a new version of the json object
+    let v = json!({ "software" : "MeldaDo", "version" : "1.0.0", "items♭":
+        [
+           {"_id" : "alice_todo_01", "title" : "Buy milk", "description": "Go to the grocery store"}
+        ]
+    })
+    .as_object()
+    .expect("Not an object")
+    .clone();
+
+    // perform another update
+    melda_alice.update(v).expect("Failed to update");
+    let info = json!({ "author" : "Alice", "description" : "Add buy milk" })
+        .as_object()
+        .expect("Not an object")
+        .clone();
+
+    // commit second change
+    let commit_result = melda_alice.commit(Some(info)).unwrap().unwrap();
+    println!("alice made another commit: {}", commit_result);
+
+    // -- Read data
+    let data = melda_alice.read().expect("Failed to read");
+    let content = serde_json::to_string_pretty(&data).unwrap();
+    println!("alice's current state{}", content);
+
+    // sharing data data
+    // copy alice to bob to create a second replica
+
+    _ = copy_recursively("todolist_alice", "todolist_bob");
+
+    let adapter_bob =
+        Box::new(FilesystemAdapter::new("todolist_bob").expect("Cannot initialize adapter"));
+
+    let melda_bob =
+        Melda::new(Arc::new(RwLock::new(adapter_bob))).expect("Failed to inizialize Melda");
+
+    // New version of the JSON object
+    let v = json!(
+        { "software" : "MeldaDo", "version" : "1.0.0", "items♭" : [
+            {"_id" : "alice_todo_01", "title" : "Buy milk", "description" : "Go to the grocery store"},
+            {"_id" : "bob_todo_01", "title" : "Pay bills", "description" : "Withdraw 500 to pay bill"},
+            {"_id" : "bob_todo_02", "title" : "Call mom", "description" : "Call mom to schedule dinner"},
+        ]
+    })
+    .as_object()
+    .expect("Not an object")
+    .clone();
+
+    // update bob's replicat
+    melda_bob.update(v).expect("Failed to update");
+    let info = json!({ "author" : "Bob", "description" : "Add some todos" })
+        .as_object()
+        .expect("Not an object")
+        .clone();
+
+    // bob commit's the result
+    let commit_result = melda_bob.commit(Some(info)).unwrap().unwrap();
+    println!("bob made a commit: {}", commit_result);
+
+    // meanwhile Alice continues to make changes...
+    let v = json!({ "software" : "MeldaDo", "version" : "1.0.0", "items♭" :
+        [
+            {"_id" : "alice_todo_02", "title" : "Take picture of our dog", "description" : "It must be a nice one"}
+        ]
+        })
+     .as_object()
+     .expect("Not an object")
+     .clone();
+
+    melda_alice.update(v).expect("Failed to update");
+    let info = json!({ "author" : "Alice", "description" : "Some more stuff to do" })
+        .as_object()
+        .expect("Not an object")
+        .clone();
+    let commit_result = melda_alice
+        .commit(Some(info))
+        .expect("commit failed")
+        .unwrap();
+    println!("meanwhile alice made yet another commit: {}", commit_result);
+
+    // Bob shares his own copy with Alice
+    melda_alice.meld(&melda_bob).expect("Failed to meld");
+    melda_alice.refresh().expect("failed to refresh");
+
+    let data = melda_alice.read().expect("Failed to read");
+
+    let content = serde_json::to_string_pretty(&data).unwrap();
+    println!("alice pulled in bob's state");
+    println!("{}", content);
+
+}
+
+pub fn copy_recursively(source: impl AsRef<Path>, destination: impl AsRef<Path>) -> io::Result<()> {
+    fs::create_dir_all(&destination)?;
+    for entry in fs::read_dir(source)? {
+        let entry = entry?;
+        let filetype = entry.file_type()?;
+        if filetype.is_dir() {
+            copy_recursively(entry.path(), destination.as_ref().join(entry.file_name()))?;
+        } else {
+            fs::copy(entry.path(), destination.as_ref().join(entry.file_name()))?;
+        }
+    }
+    Ok(())
+}