From 93b1c04a218858ecc59b6b8929103695b7b8c2a0 Mon Sep 17 00:00:00 2001
From: Carlos Maiolino <cem@toxiclabs.cc>
Date: Sat, 6 Sep 2025 09:30:14 +0200
Subject: Move rust playground here

Signed-off-by: Carlos Maiolino <cem@toxiclabs.cc>
---
 rust/chap4/borrow        | Bin 0 -> 3707760 bytes
 rust/chap4/borrow.rs     |  44 ++++++++++++++++++++++++++++++++++++++++++++
 rust/chap4/plus_one      | Bin 0 -> 3694552 bytes
 rust/chap4/plus_one.rs   |  10 ++++++++++
 rust/chap4/simple_ref    | Bin 0 -> 3699056 bytes
 rust/chap4/simple_ref.rs |  16 ++++++++++++++++
 rust/chap4/slice_me      | Bin 0 -> 3704096 bytes
 rust/chap4/slice_me.rs   |  26 ++++++++++++++++++++++++++
 rust/chap4/test          | Bin 0 -> 3693928 bytes
 rust/chap4/test.rs       |  14 ++++++++++++++
 rust/chap4/vecs          | Bin 0 -> 3702920 bytes
 rust/chap4/vecs.rs       |  11 +++++++++++
 12 files changed, 121 insertions(+)
 create mode 100755 rust/chap4/borrow
 create mode 100644 rust/chap4/borrow.rs
 create mode 100755 rust/chap4/plus_one
 create mode 100644 rust/chap4/plus_one.rs
 create mode 100755 rust/chap4/simple_ref
 create mode 100644 rust/chap4/simple_ref.rs
 create mode 100755 rust/chap4/slice_me
 create mode 100644 rust/chap4/slice_me.rs
 create mode 100755 rust/chap4/test
 create mode 100644 rust/chap4/test.rs
 create mode 100755 rust/chap4/vecs
 create mode 100644 rust/chap4/vecs.rs

(limited to 'rust/chap4')

diff --git a/rust/chap4/borrow b/rust/chap4/borrow
new file mode 100755
index 0000000..2c28095
Binary files /dev/null and b/rust/chap4/borrow differ
diff --git a/rust/chap4/borrow.rs b/rust/chap4/borrow.rs
new file mode 100644
index 0000000..36f1e9a
--- /dev/null
+++ b/rust/chap4/borrow.rs
@@ -0,0 +1,44 @@
+
+/*
+ * g1 and g2 here are "references to the m1/m2 variables,
+ * I believe they do not point directly to the data address,
+ * but to the variables addresses.
+ *
+ * This makes greet to 'borrow' the reference to the strings,
+ * and once the greet() stackframe is gone, m1 and m2 are not
+ * freed, just g1 and g2. And since they don't own anything,
+ * nothing in the heap is freed.
+ */
+fn greet(g1: &String, g2: &String) {
+    println!("{} {}", *g1, *g2);
+}
+
+fn crazy_ref() {
+
+    let x: Box<i32> = Box::new(-1);
+    let x_abs1 = i32::abs(*x);
+    let x_abs2 = x.abs();
+    assert_eq!(x_abs1, x_abs2);
+
+    let r: &Box<i32> = &x;
+    let r_abs1 = i32::abs(**r);
+    let r_abs2 = r.abs();
+    assert_eq!(r_abs1, r_abs2);
+
+    let s = String::from("Howdy");
+    let s_len1 = str::len(&s);
+    let s_len2 = s.len();
+    assert_eq!(s_len1, s_len2);
+}
+
+fn main() {
+    let m1 = String::from("Howdy");
+    let m2 = String::from("partner");
+
+    /*
+     * Pass a reference to m1 and m2 to the function parameters.
+     */
+    greet(&m1, &m2);
+    crazy_ref();
+
+}
diff --git a/rust/chap4/plus_one b/rust/chap4/plus_one
new file mode 100755
index 0000000..df7de06
Binary files /dev/null and b/rust/chap4/plus_one differ
diff --git a/rust/chap4/plus_one.rs b/rust/chap4/plus_one.rs
new file mode 100644
index 0000000..e28f415
--- /dev/null
+++ b/rust/chap4/plus_one.rs
@@ -0,0 +1,10 @@
+fn plus_one(i: i32) -> i32 {
+    i + 1
+}
+
+fn main() {
+    let i = 3;
+
+    println!("Num {}", plus_one(i));
+
+}
diff --git a/rust/chap4/simple_ref b/rust/chap4/simple_ref
new file mode 100755
index 0000000..e519673
Binary files /dev/null and b/rust/chap4/simple_ref differ
diff --git a/rust/chap4/simple_ref.rs b/rust/chap4/simple_ref.rs
new file mode 100644
index 0000000..968c025
--- /dev/null
+++ b/rust/chap4/simple_ref.rs
@@ -0,0 +1,16 @@
+fn main() {
+    let mut s = String::from("howdy");
+
+    change_me(&mut s);
+
+    let size = get_str_size(&s);
+    println!("Size of s is {size}");
+}
+
+fn get_str_size(s: &String) -> usize {
+    return s.len();
+}
+
+fn change_me(s: &mut String) {
+    s.push_str(", brilha no curintia");
+}
diff --git a/rust/chap4/slice_me b/rust/chap4/slice_me
new file mode 100755
index 0000000..d0f1d77
Binary files /dev/null and b/rust/chap4/slice_me differ
diff --git a/rust/chap4/slice_me.rs b/rust/chap4/slice_me.rs
new file mode 100644
index 0000000..da201a1
--- /dev/null
+++ b/rust/chap4/slice_me.rs
@@ -0,0 +1,26 @@
+
+/* Return the index of the first space or s.len()*/
+fn get_word_index(s: &str) -> usize {
+    let bytes = s.as_bytes();
+
+    for (i, &item) in bytes.iter().enumerate() {
+        if item == b' ' {
+            return i;
+        }
+    }
+
+    return s.len();
+}
+
+fn first_word(s: &str) -> &str {
+    let idx = get_word_index(s);
+
+    return &s[..idx];
+}
+
+fn main() {
+    let s = String::from("corno manso ronaldo curintiano");
+    let slice = first_word(&s);
+
+    println!("{slice}");
+}
diff --git a/rust/chap4/test b/rust/chap4/test
new file mode 100755
index 0000000..c45dc0c
Binary files /dev/null and b/rust/chap4/test differ
diff --git a/rust/chap4/test.rs b/rust/chap4/test.rs
new file mode 100644
index 0000000..eabcaeb
--- /dev/null
+++ b/rust/chap4/test.rs
@@ -0,0 +1,14 @@
+fn read(y: bool) {
+    if y {
+        println!("Y is true");
+    }
+
+}
+
+fn main() {
+
+    read(t);
+    let t: bool = true;
+
+    return;
+}
diff --git a/rust/chap4/vecs b/rust/chap4/vecs
new file mode 100755
index 0000000..470bd01
Binary files /dev/null and b/rust/chap4/vecs differ
diff --git a/rust/chap4/vecs.rs b/rust/chap4/vecs.rs
new file mode 100644
index 0000000..b0a76be
--- /dev/null
+++ b/rust/chap4/vecs.rs
@@ -0,0 +1,11 @@
+fn main() {
+    let mut v: Vec<i32> = vec![1, 2, 3];
+
+    /* Push an item calling method direct from Vec definition */
+    Vec::push(&mut v, 4);
+
+    /* Push an item calling the method via its object */
+    v.push(5);
+
+    println!("{:?}", v);
+}
-- 
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