[main < T] Add random walk implementation

rust/rsmgp-random-walk/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "rsmgp-random-walk"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+c_str_macro = "1.0.2"
+rsmgp-sys = { path = "../rsmgp-sys" }
+rand = "0.8.4"
+
+[lib]
+name = "rust_random_walk"
+crate-type = ["cdylib"]

rust/rsmgp-random-walk/src/lib.rs

@@ -0,0 +1,65 @@
+use c_str_macro::c_str;
+use rand::Rng;
+use rsmgp_sys::edge::*;
+use rsmgp_sys::memgraph::*;
+use rsmgp_sys::mgp::*;
+use rsmgp_sys::path::*;
+use rsmgp_sys::result::*;
+use rsmgp_sys::rsmgp::*;
+use rsmgp_sys::value::*;
+use rsmgp_sys::{close_module, define_procedure, define_type, init_module};
+use std::ffi::CString;
+use std::os::raw::c_int;
+use std::panic;
+
+define_procedure!(get, |memgraph: &Memgraph| -> Result<()> {
+    let args = memgraph.args()?;
+    let result = memgraph.result_record()?;
+    let input_start = args.value_at(0)?;
+    let input_length = args.value_at(1)?;
+    let path = if let Value::Vertex(ref vertex) = input_start {
+        Path::make_with_start(vertex, memgraph)
+    } else {
+        panic!("Failed to create path from the start vertex.");
+    }?;
+    let length = if let Value::Int(value) = input_length {
+        value
+    } else {
+        panic!("Failed to read desired path length.");
+    };
+
+    let mut vertex = if let Value::Vertex(vertex) = input_start {
+        vertex
+    } else {
+        panic!("Failed to read start vertex.");
+    };
+    let mut rng = rand::thread_rng();
+    for _ in 0..length {
+        let edges: Vec<Edge> = vertex.out_edges()?.collect();
+        if edges.is_empty() {
+            break;
+        }
+        let edge = &edges[rng.gen_range(0..edges.len())];
+        vertex = edge.to_vertex()?;
+        path.expand(edge)?;
+    }
+
+    result.insert_path(c_str!("path"), &path)?;
+    Ok(())
+});
+
+init_module!(|memgraph: &Memgraph| -> Result<()> {
+    memgraph.add_read_procedure(
+        get,
+        c_str!("get"),
+        &[
+            define_type!("start", Type::Vertex),
+            define_type!("length", Type::Int),
+        ],
+        &[],
+        &[define_type!("path", Type::Path)],
+    )?;
+    Ok(())
+});
+
+close_module!(|| -> Result<()> { Ok(()) });