From 05d78c2421a46b56485e6b60265a31e72e0a5eb6 Mon Sep 17 00:00:00 2001
From: Joel Alvarez <jeresoft@gmail.com>
Date: Wed, 29 Jul 2026 09:20:57 -0700
Subject: [PATCH] feat: add zero copy parser models

---
 .../2026-07-29-rust-performance-course.md     |  2 +-
 src/lib.rs                                    |  1 +
 src/zero_copy.rs                              | 27 +++++++++++++++++++
 tests/zero_copy_parser.rs                     | 24 +++++++++++++++++
 4 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 src/zero_copy.rs
 create mode 100644 tests/zero_copy_parser.rs

diff --git a/docs/superpowers/plans/2026-07-29-rust-performance-course.md b/docs/superpowers/plans/2026-07-29-rust-performance-course.md
index 989a48b..80f6e99 100644
--- a/docs/superpowers/plans/2026-07-29-rust-performance-course.md
+++ b/docs/superpowers/plans/2026-07-29-rust-performance-course.md
@@ -136,7 +136,7 @@ su dependencia.
 ### Capítulo 08: zero-copy, buffers y serialización
 
 - [x] #24 Especificar préstamos, buffers, parsing y costo de copias.
-- [ ] #25 Implementar y probar parsing basado en slices y buffers.
+- [x] #25 Implementar y probar parsing basado en slices y buffers.
 - [ ] #26 Escribir capítulo, diagrama, ejemplos, ejercicios y benchmarks.
 
 ### Capítulo 09: SIMD y límites de vectorización
diff --git a/src/lib.rs b/src/lib.rs
index 4927bbb..129174a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,7 @@ pub mod layout;
 pub mod locality;
 pub mod measurement;
 pub mod profile;
+pub mod zero_copy;
 
 /// Devuelve la identidad del curso para comprobar la fundación del crate.
 #[must_use]
diff --git a/src/zero_copy.rs b/src/zero_copy.rs
new file mode 100644
index 0000000..a3e7135
--- /dev/null
+++ b/src/zero_copy.rs
@@ -0,0 +1,27 @@
+//! Parsing equivalente con datos prestados o propietarios.
+
+/// Error al interpretar un segmento de pares clave-valor.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum ParseError {
+    /// El segmento no contiene el separador `=`.
+    MissingSeparator,
+}
+
+/// Interpreta pares `clave=valor` sin copiar sus fragmentos.
+pub fn parse_borrowed(input: &str) -> Result<Vec<(&str, &str)>, ParseError> {
+    input
+        .split(';')
+        .filter(|segment| !segment.is_empty())
+        .map(|segment| segment.split_once('=').ok_or(ParseError::MissingSeparator))
+        .collect()
+}
+
+/// Interpreta el mismo formato y crea una representación propietaria.
+pub fn parse_owned(input: &str) -> Result<Vec<(String, String)>, ParseError> {
+    parse_borrowed(input).map(|pairs| {
+        pairs
+            .into_iter()
+            .map(|(key, value)| (key.to_owned(), value.to_owned()))
+            .collect()
+    })
+}
diff --git a/tests/zero_copy_parser.rs b/tests/zero_copy_parser.rs
new file mode 100644
index 0000000..2baf6b0
--- /dev/null
+++ b/tests/zero_copy_parser.rs
@@ -0,0 +1,24 @@
+use rust_performance::zero_copy::{parse_borrowed, parse_owned, ParseError};
+
+#[test]
+fn borrowed_and_owned_parsers_preserve_the_same_pairs() {
+    let borrowed = parse_borrowed("lang=rust;mode=release").expect("valid input");
+    let owned = parse_owned("lang=rust;mode=release").expect("valid input");
+
+    assert_eq!(borrowed, [("lang", "rust"), ("mode", "release")]);
+    assert_eq!(
+        owned,
+        [
+            (String::from("lang"), String::from("rust")),
+            (String::from("mode"), String::from("release"))
+        ]
+    );
+}
+
+#[test]
+fn parser_rejects_segments_without_an_equals_sign() {
+    assert_eq!(
+        parse_borrowed("lang=rust;invalid"),
+        Err(ParseError::MissingSeparator)
+    );
+}