Merge branch 'mr/483-create-lab-for-module-pattern-matching' into 'master'

Resolve "Create Lab for Module: Pattern Matching"

Closes #483

See merge request feng/training/material!559

Author: Dana Binkley

courses/rust_essentials/080_pattern_matching/88-pattern_matching.lab.rst

@@ -1,52 +1,17 @@
-=================================
-Exercise: Expression Evaluation
-=================================
+=====
+Lab
+=====
 
-----------------------------------
-Expression Evaluation Background
-----------------------------------
+------------------
+Lab Instructions
+------------------
 
-Let's write a simple recursive evaluator for arithmetic expressions.
+- Solve for compilation errors
 
-An example of a small arithmetic expression could be :rust:`10 + 20`, which
-evaluates to :rust:`30`. We can represent the expression as a tree:
+- Follow the hints!
 
-.. image:: comprehensive_rust_training/pattern_matching_exercise_1.svg
-   :width: 40%
+- Success is
 
-A bigger and more complex expression would be
-:rust:`(10 * 9) + ((3 - 4) * 5)`, which evaluate to :rust:`85`. We represent
-this as a much bigger tree:
+    - Code that compiles
 
-.. image:: comprehensive_rust_training/pattern_matching_exercise_2.svg
-
----------------------------------
-Expression Evaluation Problem
----------------------------------
-
-In code, we will represent the tree with two types:
-
-.. container:: source_include 080_pattern_matching/src/080_pattern_matching.rs :start-after://ANCHOR-operation :end-before://ANCHOR-expression :code:rust
-
-.. container:: source_include 080_pattern_matching/src/080_pattern_matching.rs :start-after://ANCHOR-expression :end-before://ANCHOR-eval :code:rust
-
-And then create an evaluator:
-
-.. code:: rust
-
-   fn eval(e: Expression) -> i64 {
-       todo!()
-   }
-
-.. container:: source_include 080_pattern_matching/src/080_pattern_matching.rs :start-after://ANCHOR-main :code:rust
-
-.. note:: The :rust:`Box` type here is a smart pointer, and will be covered in detail later in the course. To evaluate a boxed expression, use the deref operator (:rust:`*`) to "unbox" it: :rust:`eval(*boxed_expr)`.
-
-Copy and paste the code into the Rust playground, and begin implementing
-:rust:`eval`.
-
----------------------------------
-Expression Evaluation Solution
----------------------------------
-
-.. container:: source_include 080_pattern_matching/src/080_pattern_matching.rs :start-after://ANCHOR-eval :end-before://ANCHOR-tests :code:rust
+    - ...and that follows any behavior indicated within the hints!

courses/rust_essentials/080_pattern_matching/lab/answer/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "lab"
+name = "answer"
 version = "1.0.0"
 edition = "2024"
 

courses/rust_essentials/080_pattern_matching/lab/answer/src/main.rs

@@ -1,3 +1,119 @@
+//! Lab (answer)
+//! Pattern Matching
+//!
+#[allow(dead_code)]
+#[allow(unused_variables)]
 fn main() {
-    println!("TBD");
+    
+    // TASK 1 - Exhaustiveness in 'match'
+    // Hint: All possible cases must be handled
+    enum Status {
+        Online,
+        Offline,
+        Busy,
+    }
+
+    let current_status = Status::Online;
+    match current_status {
+        Status::Online => println!("User is online"),
+        Status::Offline => println!("User is offline"),
+        // Fix: Added the missing variant to satisfy exhaustiveness
+        Status::Busy => println!("User is busy"),
+    }
+
+
+    // TASK 2 - Refutable Pattern in a 'let' Binding
+    // Hint: Every 'let' binding uses a pattern, but simple bindings require irrefutable patterns
+    let secret_value = Some(42);
+    
+    // Fix: Used 'if let' to handle the conditional/refutable pattern
+    if let Some(x) = secret_value {
+        println!("The secret is {}", x);
+    }
+
+
+    // TASK 3 - Ignoring Fields in Struct Destructuring
+    // Hint: Unused fields may be ignored using rest pattern to capture specific named fields and ignore remaining
+    struct Player {
+        name: String,
+        health: u32,
+        mana: u32,
+    }
+
+    let p = Player { name: String::from("Hero"), health: 100, mana: 50 };
+    
+    // Fix: Added '..' to explicitly ignore the 'mana' field
+    let Player { name, health, .. } = p;
+
+
+    // TASK 4 - Destructuring Variant Data
+    // Hint: You must keep the parentheses for variants with data, even if you are ignoring the content
+    enum Alert {
+        Clear,
+        Warning(String),
+    }
+
+    let a = Alert::Warning(String::from("Low Battery"));
+    match a {
+        // Fix: Added '(_)' to properly account for the payload while ignoring it
+        Alert::Warning(_) => println!("Received a warning, ignoring details"),
+        Alert::Clear => println!("All clear"),
+    }
+
+
+    // TASK 5 - Match Guards and Exhaustiveness
+    // Hint: Guards are dynamic, compiler usually requires a "catch-all" arm (_) when using match guards
+    let temperature = 30;
+    match temperature {
+        t if t > 25 => println!("Hot"),
+        t if t <= 25 => println!("Cool"),
+        _ => unreachable!(), // Fix: Added the wildcard '_' catch-all arm
+    }
+
+
+    // TASK 6 - Longhand Struct Destructuring and Renaming
+    // Hint: Use 'field: variable' to rename data as it is extracted
+    struct Coordinates {
+        x: i32,
+        y: i32,
+    }
+
+    let c = Coordinates { x: 5, y: 10 };
+    // Fix: Swapped the order to correctly map the struct fields to the new local variables
+    let Coordinates { x: my_x, y: my_y } = c;
+
+    println!("The coordinates are: {},{}", my_x, my_y);
+
+
+    // TASK 7 - Destructuring Struct Variants
+    // Hint: Struct variants use named fields, patterns must match fields by name using {} instead of ()
+    enum Geometry {
+        Rectangle { width: u32, height: u32 },
+    }
+
+    let geo = Geometry::Rectangle { width: 10, height: 20 };
+    match geo {
+        // Fix: Changed the tuple syntax '()' to struct syntax '{}'
+        Geometry::Rectangle { width, height } => println!("{}x{}", width, height),
+    }
+
+
+    // TASK 8 - "if let" Syntax Order
+    // Hint: "if let" follows assignment order: Pattern = value
+    let optional_code = Some(777);
+    
+    // Fix: Reordered the expression so the pattern is on the left and the value is on the right
+    if let Some(code) = optional_code {
+        println!("Code is {}", code);
+    }
+
+
+    // TASK 9 - Variable Bindings with Ranges
+    // Hint: Use the '@' operator to give a name to a value while checking it against a range
+    let dice_roll = 4;
+    match dice_roll {
+        // Fix: Placed the identifier 'roll' before the '@' and the range pattern
+        roll @ 1..=6 => println!("Rolled a {}", roll),
+        _ => println!("Invalid roll"),
+    }
 }

courses/rust_essentials/080_pattern_matching/lab/prompt/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "lab"
+name = "prompt"
 version = "1.0.0"
 edition = "2024"
 

courses/rust_essentials/080_pattern_matching/lab/prompt/src/main.rs

@@ -1,3 +1,110 @@
+//! Lab (prompt)
+//! Pattern Matching
+//!
+//! Fix all the compile errors below by following the hints provided 
+//! 
+#[allow(dead_code)]
+#[allow(unused_variables)]
 fn main() {
-    println!("TBD");
+    
+    // TASK 1 - Exhaustiveness in 'match'
+    // Hint: All possible cases must be handled
+    enum Status {
+        Online,
+        Offline,
+        Busy,
+    }
+
+    let current_status = Status::Online;
+    match current_status {
+        Status::Online => println!("User is online"),
+        Status::Offline => println!("User is offline"),
+    }
+
+
+    // TASK 2 - Refutable Pattern in a 'let' Binding
+    // Hint: Every 'let' binding uses a pattern, but simple bindings require irrefutable patterns
+    let secret_value = Some(42);
+    
+    let Some(x) = secret_value;
+    println!("The secret is {}", x);
+
+
+    // TASK 3 - Ignoring Fields in Struct Destructuring
+    // Hint: Unused fields may be ignored using rest pattern to capture specific named fields and ignore remaining
+    struct Player {
+        name: String,
+        health: u32,
+        mana: u32,
+    }
+
+    let p = Player { name: String::from("Hero"), health: 100, mana: 50 };
+    
+    let Player { name, health } = p;
+
+
+    // TASK 4 - Destructuring Variant Data
+    // Hint: You must keep the parentheses for variants with data, even if you are ignoring the content
+    enum Alert {
+        Clear,
+        Warning(String),
+    }
+
+    let a = Alert::Warning(String::from("Low Battery"));
+    match a {
+        Alert::Warning => println!("Received a warning, ignoring details"),
+        Alert::Clear => println!("All clear"),
+    }
+
+
+    // TASK 5 - Match Guards and Exhaustiveness
+    // Hint: Guards are dynamic, compiler usually requires a "catch-all" arm (_) when using match guards
+    let temperature = 30;
+    match temperature {
+        t if t > 25 => println!("Hot"),
+        t if t <= 25 => println!("Cool"),
+    }
+
+
+    // TASK 6 - Longhand Struct Destructuring and Renaming
+    // Hint: Use 'field: variable' to rename data as it is extracted
+    struct Coordinates {
+        x: i32,
+        y: i32,
+    }
+
+    let c = Coordinates { x: 5, y: 10 };
+    let Coordinates { my_x: x, my_y: y } = c;
+    
+    println!("The coordinates are: {},{}", my_x, my_y);
+
+
+    // TASK 7 - Destructuring Struct Variants
+    // Hint: Struct variants use named fields, patterns must match fields by name using {} instead of ()
+    enum Geometry {
+        Rectangle { width: u32, height: u32 },
+    }
+
+    let geo = Geometry::Rectangle { width: 10, height: 20 };
+    match geo {
+        Geometry::Rectangle(width, height) => println!("{}x{}", width, height),
+    }
+
+
+    // TASK 8 - "if let" Syntax Order
+    // Hint: "if let" follows assignment order: Pattern = value
+    let optional_code = Some(777);
+    
+    if let optional_code = Some(code) {
+        println!("Code is {}", code);
+    }
+
+
+    // TASK 9 - Variable Bindings with Ranges
+    // Hint: Use the '@' operator to give a name to a value while checking it against a range
+    let dice_roll = 4;
+    match dice_roll {
+        1..=6 @ roll => println!("Rolled a {}", roll),
+        _ => println!("Invalid roll"),
+    }
 }