Add ability to extend cheatsheets (#382)v2.9.0

Fixes #377

8 files changed, 106 insertions, 26 deletions

diff --git a/Cargo.lock b/Cargo.lock
index ca7bf1b..8ce2c91 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -174,7 +174,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "navi"
-version = "2.8.0"
+version = "2.9.0"
 dependencies = [
  "anyhow 1.0.27 (registry+https://github.com/rust-lang/crates.io-index)",
  "dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/Cargo.toml b/Cargo.toml
index c055a26..8f381b6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "navi"
-version = "2.8.0"
+version = "2.9.0"
 authors = ["Denis Isidoro <denis_isidoro@live.com>"]
 edition = "2018"
 description = "An interactive cheatsheet tool for the command-line"
diff --git a/README.md b/README.md
index 8b69e49..53ec659 100644
--- a/README.md
+++ b/README.md
@@ -185,7 +185,8 @@ $ branch: git branch | awk '{print $NF}'
 - lines starting with `%` determine the start of a new cheatsheet and should contain tags, useful for searching;
 - lines starting with `#` should be descriptions of commands;
 - lines starting with `;` are ignored. You can use them for metacomments;
-- lines starting with `$` should contain commands that generate a list of possible values for a given argument;
+- lines starting with `$` should contain [commands that generate a list of possible values for a given argument](#variables);
+- lines starting with `@` should contain [tags whose associated cheatsheet you want to base on](#extending-cheatsheets);
 - all the other non-empty lines are considered as executable commands.
 
 It's irrelevant how many files are used to store cheatsheets. They can be all in a single file if you wish, as long as you split them accordingly with lines starting with `%`.
@@ -232,7 +233,16 @@ In addition, it's possible to forward the following parameters to `fzf`:
 
 ### Variable dependency
 
-The command for generating possible inputs can refer previous variables:
+The command for generating possible inputs can implicitly refer previous variables by using the `<varname>` syntax:
+```sh
+# Should print /my/pictures/wallpapers
+echo "<wallpaper_folder>"
+
+$ pictures_folder: echo "/my/pictures"
+$ wallpaper_folder: echo "<pictures_folder>/wallpapers"
+```
+
+If you want to make dependencies explicit, you can use the `$varname` syntax:
 ```sh
 # If you select "hello" for <x>, the possible values of <y> will be "hello foo" and "hello bar"
 echo <x> <y>
@@ -244,13 +254,26 @@ $ x: echo "hello hi" | tr ' ' '\n'
 $ y: echo "$x foo;$x bar" | tr ';' '\n'
 ```
 
-If you want to have implicit variable dependency, you can use the `<varname>` syntax inside a variable command:
+### Extending cheatsheets
+
+With the `@ same tags from other cheatsheet` syntax you can reuse the same variable in multiple cheatsheets. 
+
 ```sh
-# Should print /my/pictures/wallpapers
-echo "<wallpaper_folder>"
+% dirs, common
 
 $ pictures_folder: echo "/my/pictures"
-$ wallpaper_folder: echo "<pictures_folder>/wallpapers"
+
+% wallpapers
+@ dirs, common
+
+# Should print /my/pictures/wallpapers
+echo "<pictures_folder>/wallpapers"
+
+% screenshots
+@ dirs, common
+
+# Should print /my/pictures/screenshots
+echo "<pictures_folder>/screenshots"
 ```
 
 ### Multiline snippets
diff --git a/src/flows/alfred.rs b/src/flows/alfred.rs
index 4ca1f56..acfa7e3 100644
--- a/src/flows/alfred.rs
+++ b/src/flows/alfred.rs
@@ -66,7 +66,7 @@ pub fn suggestions(config: Config, dry_run: bool) -> Result<(), Error> {
     let capture = display::VAR_REGEX.captures_iter(&snippet).next();
     let bracketed_varname = &(capture.expect("Invalid capture"))[0];
     let varname = &bracketed_varname[1..bracketed_varname.len() - 1];
-    let command = variables.get(&tags, &varname);
+    let command = variables.get_suggestion(&tags, &varname);
 
     if dry_run {
         if command.is_none() {
diff --git a/src/flows/core.rs b/src/flows/core.rs
index 3b8055a..b5341bc 100644
--- a/src/flows/core.rs
+++ b/src/flows/core.rs
@@ -148,7 +148,7 @@ fn replace_variables_from_snippet(
             e
         } else {
             variables
-                .get(&tags, &variable_name)
+                .get_suggestion(&tags, &variable_name)
                 .ok_or_else(|| anyhow!("No suggestions"))
                 .and_then(|suggestion| {
                     let mut new_suggestion = suggestion.clone();
diff --git a/src/parser.rs b/src/parser.rs
index ede15be..de5e7ed 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -160,7 +160,6 @@ fn read_file(
 
         // duplicate
         if !tags.is_empty() && !comment.is_empty() {}
-
         // blank
         if line.is_empty() {
         }
@@ -176,6 +175,15 @@ fn read_file(
                 String::from("")
             };
         }
+        // depedency
+        else if line.starts_with('@') {
+            let tags_dependency = if line.len() > 2 {
+                String::from(&line[2..])
+            } else {
+                String::from("")
+            };
+            variables.insert_dependency(&tags, &tags_dependency);
+        }
         // metacomment
         else if line.starts_with(';') {
         }
@@ -204,7 +212,7 @@ fn read_file(
                     path
                 )
             })?;
-            variables.insert(&tags, &variable, (String::from(command), opts));
+            variables.insert_suggestion(&tags, &variable, (String::from(command), opts));
         }
         // snippet
         else {
@@ -331,7 +339,7 @@ mod tests {
                 ..Default::default()
             }),
         );
-        let actual_suggestion = variables.get("ssh", "user");
+        let actual_suggestion = variables.get_suggestion("ssh", "user");
         assert_eq!(Some(&expected_suggestion), actual_suggestion);
     }
 
diff --git a/src/structures/cheat.rs b/src/structures/cheat.rs
index e695063..3b5a7ce 100644
--- a/src/structures/cheat.rs
+++ b/src/structures/cheat.rs
@@ -5,26 +5,56 @@ use std::collections::HashMap;
 pub type Suggestion = (String, Option<Opts>);
 
 #[derive(Clone)]
-pub struct VariableMap(HashMap<u64, HashMap<String, Suggestion>>);
+pub struct VariableMap {
+    variables: HashMap<u64, HashMap<String, Suggestion>>,
+    dependencies: HashMap<u64, Vec<u64>>,
+}
 
 impl VariableMap {
     pub fn new() -> Self {
-        Self(HashMap::new())
+        Self {
+            variables: HashMap::new(),
+            dependencies: HashMap::new(),
+        }
+    }
+
+    pub fn insert_dependency(&mut self, tags: &str, tags_dependency: &str) {
+        let k = tags.hash_line();
+        if let Some(v) = self.dependencies.get_mut(&k) {
+            v.push(tags_dependency.hash_line());
+        } else {
+            let mut v: Vec<u64> = Vec::new();
+            v.push(tags_dependency.hash_line());
+            self.dependencies.insert(k, v);
+        }
     }
 
-    pub fn insert(&mut self, tags: &str, variable: &str, value: Suggestion) {
+    pub fn insert_suggestion(&mut self, tags: &str, variable: &str, value: Suggestion) {
         let k1 = tags.hash_line();
         let k2 = String::from(variable);
-        if let Some(m) = self.0.get_mut(&k1) {
+        if let Some(m) = self.variables.get_mut(&k1) {
             m.insert(k2, value);
         } else {
             let mut m = HashMap::new();
             m.insert(k2, value);
-            self.0.insert(k1, m);
+            self.variables.insert(k1, m);
         }
     }
 
-    pub fn get(&self, tags: &str, variable: &str) -> Option<&Suggestion> {
-        self.0.get(&tags.hash_line())?.get(variable)
+    pub fn get_suggestion(&self, tags: &str, variable: &str) -> Option<&Suggestion> {
+        let k = tags.hash_line();
+        let res = self.variables.get(&k)?.get(variable);
+        if res.is_some() {
+            return res;
+        }
+        if let Some(dependency_keys) = self.dependencies.get(&k) {
+            for dependency_key in dependency_keys {
+                let res = self.variables.get(&dependency_key)?.get(variable);
+                if res.is_some() {
+                    return res;
+                }
+            }
+        }
+        None
     }
 }
diff --git a/tests/no_prompt_cheats/cases.cheat b/tests/no_prompt_cheats/cases.cheat
index e3f07dd..d60e859 100644
--- a/tests/no_prompt_cheats/cases.cheat
+++ b/tests/no_prompt_cheats/cases.cheat
@@ -1,6 +1,6 @@
 ; author: CI/CD
 
-% test, ci/cd
+% test, first
 
 # trivial case -> "foo"
 echo "foo"
@@ -34,9 +34,6 @@ echo "<x> <x2> <y> <x>"
 # variable dependency, we can ignore intermediate values -> "12"
 : <x>; echo "<x2>"
 
-# nested used value -> "path: /my/pictures/wallpapers"
-echo "path: <wallpaper_folder>"
-
 # nested unused value -> "path: /my/pictures"
 echo "path: <pictures_folder>"
 
@@ -47,7 +44,29 @@ $ language: echo '0  rust      rust-lang.org' --- --column 2
 $ language2: echo '1;clojure;clojure.org' --- --column 2 --delimiter ';'
 $ multiword: echo 'foo bar'
 $ pictures_folder: echo "/my/pictures"
-$ wallpaper_folder: echo "<pictures_folder>/wallpapers"
 
 # this should be displayed -> "hi"
-echo hi
\ No newline at end of file
+echo hi
+
+
+% test, second
+
+@ test, first
+@ test, third
+
+# nested used value -> "path: /my/pictures/wallpapers"
+echo "path: <wallpaper_folder>"
+
+# same command as before -> "12"
+: <x>; echo "<x2>"
+
+# the order isn't relevant -> "br"
+echo "<country>"
+
+$ wallpaper_folder: echo "<pictures_folder>/wallpapers"
+
+
+% test, third
+
+; this cheathsheet doesnt have any commands
+$ country: echo "br"
\ No newline at end of file