From f9dcd6d48d34d932abfd10e767803813c10b7cbe Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Tue, 5 Feb 2019 10:22:35 -0500
Subject: [PATCH] Add reference_counting example

---
 .idea/misc.xml                 |  1 +
 .idea/rust.iml                 |  5 +++
 .idea/workspace.xml            | 64 +++++++++++++++-------------------
 reference_counting/Cargo.toml  |  7 ++++
 reference_counting/src/main.rs | 19 ++++++++++
 5 files changed, 60 insertions(+), 36 deletions(-)
 create mode 100644 reference_counting/Cargo.toml
 create mode 100644 reference_counting/src/main.rs

diff --git a/.idea/misc.xml b/.idea/misc.xml
index 8ca6f05..465fbc7 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -25,6 +25,7 @@
     <cargoProject FILE="$PROJECT_DIR$/minigrep_v2/Cargo.toml" />
     <cargoProject FILE="$PROJECT_DIR$/add/Cargo.toml" />
     <cargoProject FILE="$PROJECT_DIR$/smart_pointers/Cargo.toml" />
+    <cargoProject FILE="$PROJECT_DIR$/reference_counting/Cargo.toml" />
   </component>
   <component name="ComposerJsonPluginSettings">
     <unboundedVersionInspectionSettings>
diff --git a/.idea/rust.iml b/.idea/rust.iml
index bfb4a8b..73d9872 100644
--- a/.idea/rust.iml
+++ b/.idea/rust.iml
@@ -102,6 +102,10 @@
       <sourceFolder url="file://$MODULE_DIR$/smart_pointers/examples" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/smart_pointers/tests" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/smart_pointers/benches" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/reference_counting/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/reference_counting/examples" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/reference_counting/tests" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/reference_counting/benches" isTestSource="true" />
       <excludeFolder url="file://$MODULE_DIR$/add/add-one/target" />
       <excludeFolder url="file://$MODULE_DIR$/add/adder/target" />
       <excludeFolder url="file://$MODULE_DIR$/adder/target" />
@@ -120,6 +124,7 @@
       <excludeFolder url="file://$MODULE_DIR$/minigrep_v2/target" />
       <excludeFolder url="file://$MODULE_DIR$/modules/target" />
       <excludeFolder url="file://$MODULE_DIR$/rectangles/target" />
+      <excludeFolder url="file://$MODULE_DIR$/reference_counting/target" />
       <excludeFolder url="file://$MODULE_DIR$/references/target" />
       <excludeFolder url="file://$MODULE_DIR$/scope/target" />
       <excludeFolder url="file://$MODULE_DIR$/slices/target" />
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 7405fa5..5369e4f 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -15,29 +15,14 @@
   <component name="FileEditorManager">
     <leaf>
       <file pinned="false" current-in-tab="true">
-        <entry file="file://$PROJECT_DIR$/smart_pointers/src/main.rs">
+        <entry file="file://$PROJECT_DIR$/reference_counting/src/main.rs">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="32">
-              <caret line="2" lean-forward="true" selection-start-line="2" selection-end-line="2" />
-              <folding>
-                <element signature="e#68#69#0" expanded="true" />
-                <element signature="e#91#92#0" expanded="true" />
-                <element signature="e#200#201#0" expanded="true" />
-                <element signature="e#216#217#0" expanded="true" />
-                <element signature="e#351#352#0" expanded="true" />
-                <element signature="e#433#434#0" expanded="true" />
-                <element signature="e#244#245#0" expanded="true" />
-                <element signature="e#261#262#0" expanded="true" />
-              </folding>
+            <state relative-caret-position="224">
+              <caret line="14" column="13" selection-start-line="14" selection-start-column="13" selection-end-line="14" selection-end-column="13" />
             </state>
           </provider>
         </entry>
       </file>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/smart_pointers/src/lib.rs">
-          <provider selected="true" editor-type-id="text-editor" />
-        </entry>
-      </file>
     </leaf>
   </component>
   <component name="FileTemplateManagerImpl">
@@ -107,6 +92,7 @@
         <option value="$PROJECT_DIR$/add/add-one/src/lib.rs" />
         <option value="$PROJECT_DIR$/smart_pointers/src/lib.rs" />
         <option value="$PROJECT_DIR$/smart_pointers/src/main.rs" />
+        <option value="$PROJECT_DIR$/reference_counting/src/main.rs" />
       </list>
     </option>
   </component>
@@ -140,12 +126,12 @@
             <path>
               <item name="rust" type="3d21c010:ScopeViewTreeModel$ProjectNode" />
               <item name="rust" type="2674bda8:ScopeViewTreeModel$GroupNode" />
-              <item name="smart_pointers" type="9f88c78c:ScopeViewTreeModel$FileNode" />
+              <item name="reference_counting" type="9f88c78c:ScopeViewTreeModel$FileNode" />
             </path>
             <path>
               <item name="rust" type="3d21c010:ScopeViewTreeModel$ProjectNode" />
               <item name="rust" type="2674bda8:ScopeViewTreeModel$GroupNode" />
-              <item name="smart_pointers" type="9f88c78c:ScopeViewTreeModel$FileNode" />
+              <item name="reference_counting" type="9f88c78c:ScopeViewTreeModel$FileNode" />
               <item name="src" type="9f88c78c:ScopeViewTreeModel$FileNode" />
             </path>
           </expand>
@@ -179,7 +165,7 @@
   </component>
   <component name="PropertiesComponent">
     <property name="JavaScriptWeakerCompletionTypeGuess" value="true" />
-    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1549379395077" />
+    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1549380100372" />
     <property name="javascript.nodejs.core.library.configured.version" value="7.1.0" />
     <property name="js.eslint.eslintPackage" value="$USER_HOME$/.yarn-config/global/node_modules/.bin/eslint" />
     <property name="js.eslint.nodeInterpreter" value="project" />
@@ -207,7 +193,7 @@
       </list>
     </option>
   </component>
-  <component name="RunManager" selected="Cargo Command.Run smart_pointers">
+  <component name="RunManager" selected="Cargo Command.Run reference_counting">
     <configuration name="&lt;template&gt;" type="TestNG" default="true" selected="false">
       <option name="MAIN_CLASS_NAME" />
       <option name="VM_PARAMETERS" value="-ea" />
@@ -226,6 +212,16 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
+    <configuration name="Run reference_counting" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
+      <option name="channel" value="DEFAULT" />
+      <option name="command" value="run --package reference_counting --bin reference_counting" />
+      <option name="allFeatures" value="false" />
+      <option name="nocapture" value="false" />
+      <option name="backtrace" value="SHORT" />
+      <option name="workingDirectory" value="file://$PROJECT_DIR$/reference_counting" />
+      <envs />
+      <method v="2" />
+    </configuration>
     <configuration name="Run smart_pointers" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
       <option name="channel" value="DEFAULT" />
       <option name="command" value="run --package smart_pointers --bin smart_pointers" />
@@ -246,16 +242,6 @@
       <envs />
       <method v="2" />
     </configuration>
-    <configuration name="Test filters_by_size" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
-      <option name="channel" value="DEFAULT" />
-      <option name="command" value="test --package closures --lib filters_by_size -- --exact" />
-      <option name="allFeatures" value="false" />
-      <option name="nocapture" value="false" />
-      <option name="backtrace" value="SHORT" />
-      <option name="workingDirectory" value="file://$PROJECT_DIR$/closures" />
-      <envs />
-      <method v="2" />
-    </configuration>
     <configuration name="Test lib::tests (1)" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
       <option name="channel" value="DEFAULT" />
       <option name="command" value="test --package minigrep_v2 --lib tests" />
@@ -285,11 +271,11 @@
     </configuration>
     <recent_temporary>
       <list>
+        <item itemvalue="Cargo Command.Run reference_counting" />
         <item itemvalue="Cargo Command.Run smart_pointers" />
         <item itemvalue="Cargo Command.Test lib::tests (1)" />
         <item itemvalue="Cargo Command.Test using_other_iterator_trait_methods" />
         <item itemvalue="Cargo Command.Test calling_next_directly" />
-        <item itemvalue="Cargo Command.Test filters_by_size" />
       </list>
     </recent_temporary>
   </component>
@@ -731,13 +717,12 @@
     </entry>
     <entry file="file://$PROJECT_DIR$/smart_pointers/src/main.rs">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="32">
-          <caret line="2" lean-forward="true" selection-start-line="2" selection-end-line="2" />
+        <state relative-caret-position="256">
+          <caret line="16" column="4" selection-start-line="16" selection-start-column="4" selection-end-line="16" selection-end-column="4" />
           <folding>
             <element signature="e#68#69#0" expanded="true" />
             <element signature="e#91#92#0" expanded="true" />
             <element signature="e#200#201#0" expanded="true" />
-            <element signature="e#216#217#0" expanded="true" />
             <element signature="e#351#352#0" expanded="true" />
             <element signature="e#433#434#0" expanded="true" />
             <element signature="e#244#245#0" expanded="true" />
@@ -746,5 +731,12 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/reference_counting/src/main.rs">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="224">
+          <caret line="14" column="13" selection-start-line="14" selection-start-column="13" selection-end-line="14" selection-end-column="13" />
+        </state>
+      </provider>
+    </entry>
   </component>
 </project>
\ No newline at end of file
diff --git a/reference_counting/Cargo.toml b/reference_counting/Cargo.toml
new file mode 100644
index 0000000..edcb9c1
--- /dev/null
+++ b/reference_counting/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "reference_counting"
+version = "0.1.0"
+authors = ["Timothy Warren <twarren@nabancard.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/reference_counting/src/main.rs b/reference_counting/src/main.rs
new file mode 100644
index 0000000..1ea8326
--- /dev/null
+++ b/reference_counting/src/main.rs
@@ -0,0 +1,19 @@
+enum List {
+    Cons(i32, Rc<List>),
+    Nil,
+}
+
+use List::{Cons, Nil};
+use std::rc::Rc;
+
+fn main() {
+    let a = Rc::new(Cons(5, Rc::new(Cons(10, Rc::new(Nil)))));
+    println!("count after creating a = {}", Rc::strong_count(&a));
+    let _b = Cons(3, Rc::clone(&a));
+    println!("count after creating b = {}", Rc::strong_count(&a));
+    {
+        let _c = Cons(4, Rc::clone(&a));
+        println!("count after creating c = {}", Rc::strong_count(&a));
+    }
+    println!("count after c goes out of scope = {}", Rc::strong_count(&a));
+}