Improve API by introducing a PlatformType struct

The goal is supporting the special `all` platform that results in pages
for all platforms being listed when calling `--list`. It's part of the
tldr client specification.

However, `All` should not be a variant of the `PlatformType` enum,
because `Current` isn't a `PlatformType` either. Thus, we accept the
string `all` but convert it into the current platform when parsing.

For consistency, the same is done when no platform is specified, by
introducing yet another possible value `current` which is used by
default. This way, we get rid of the `Option`.

To simplify handling of os / platform arguments, a conflict between
`--platform` and `--os` was introduced.

docs/src/usage.txt

@@ -14,7 +14,7 @@ OPTIONS:
     -l, --list                   List all commands in the cache
     -f, --render <FILE>          Render a specific markdown file
     -p, --platform <PLATFORM>    Override the operating system [possible values: linux, macos,
-                                 windows, sunos, osx]
+                                 windows, sunos, all]
     -o, --os <OS>                Deprecated alias of `platform`
     -L, --language <LANGUAGE>    Override the language
     -u, --update                 Update the local cache

src/cache.rs

@@ -16,7 +16,7 @@ use zip::ZipArchive;
 
 use crate::{
     error::TealdeerError::{self, CacheError, UpdateError},
-    types::{PathSource, PlatformType},
+    types::{PathSource, PlatformStrategy, PlatformType},
 };
 
 static CACHE_DIR_ENV_VAR: &str = "TEALDEER_CACHE_DIR";
@@ -27,7 +27,7 @@ static TLDR_OLD_PAGES_DIR: &str = "tldr-master";
 #[derive(Debug)]
 pub struct Cache {
     url: String,
-    platform: PlatformType,
+    platform: PlatformStrategy,
 }
 
 #[derive(Debug)]
@@ -64,7 +64,7 @@ pub enum CacheFreshness {
 }
 
 impl Cache {
-    pub fn new<S>(url: S, platform: PlatformType) -> Self
+    pub fn new<S>(url: S, platform: PlatformStrategy) -> Self
     where
         S: Into<String>,
     {
@@ -196,11 +196,11 @@ impl Cache {
 
     /// Return the platform directory.
     fn get_platform_dir(&self) -> &'static str {
-        match self.platform {
-            PlatformType::Linux => "linux",
-            PlatformType::OsX => "osx",
-            PlatformType::SunOs => "sunos",
-            PlatformType::Windows => "windows",
+        match self.platform.platform_type {
+            PlatformType::Linux { .. } => "linux",
+            PlatformType::OsX { .. } => "osx",
+            PlatformType::SunOs { .. } => "sunos",
+            PlatformType::Windows { .. } => "windows",
         }
     }
 
@@ -305,7 +305,7 @@ impl Cache {
         let mut pages = WalkDir::new(platforms_dir)
             .min_depth(1) // Skip root directory
             .into_iter()
-            .filter_entry(|e| should_walk(e)) // Filter out pages for other architectures
+            .filter_entry(|e| self.platform.list_all || should_walk(e)) // Filter out pages for other architectures
             .filter_map(Result::ok) // Convert results to options, filter out errors
             .filter_map(|e| {
                 let path = e.path();

src/main.rs

@@ -40,7 +40,7 @@ use crate::{
     error::TealdeerError::ConfigError,
     extensions::Dedup,
     output::print_page,
-    types::{ColorOptions, PlatformType},
+    types::{ColorOptions, PlatformStrategy, PlatformType},
     utils::{print_error, print_warning},
 };
 
@@ -80,22 +80,28 @@ struct Args {
     )]
     render: Option<PathBuf>,
 
-    /// Override the operating system
+    /// Override the operating system [possible values: linux, macos, windows, sunos, all]
     #[clap(
         short = 'p',
         long = "platform",
-        possible_values = ["linux", "macos", "windows", "sunos", "osx"],
+        possible_values = ["linux", "macos", "windows", "sunos", "osx", "current", "all"],
+        default_value = "current",
+        hide_possible_values = true,
+        hide_default_value = true,
     )]
-    platform: Option<PlatformType>,
+    platform: PlatformStrategy,
 
     /// Deprecated alias of `platform`
     #[clap(
         short = 'o',
         long = "os",
-        possible_values = ["linux", "macos", "windows", "sunos", "osx"],
+        conflicts_with = "platform",
+        possible_values = ["linux", "macos", "windows", "sunos", "osx", "current", "all"],
+        default_value = "current",
         hide_possible_values = true,
+        hide_default_value = true,
     )]
-    os: Option<PlatformType>,
+    os: PlatformStrategy,
 
     /// Override the language
     #[clap(short = 'L', long = "language")]
@@ -400,13 +406,14 @@ fn main() {
             "The -m / --markdown flag is deprecated, use -r / --raw instead",
         );
     }
-    if args.os.is_some() {
+    let default_platform = PlatformType::current();
+    if args.os.platform_type != default_platform || args.os.list_all {
         print_warning(
             enable_styles,
             "The -o / --os flag is deprecated, use -p / --platform instead",
         );
+        args.platform = args.os;
     }
-    args.platform = args.platform.or(args.os);
 
     // Show config file and path, pass through
     if args.config_path {
@@ -442,9 +449,6 @@ fn main() {
         configure_pager(enable_styles);
     }
 
-    // Specify target OS
-    let platform: PlatformType = args.platform.unwrap_or_else(PlatformType::current);
-
     // If a local file was passed in, render it and exit
     if let Some(file) = args.render {
         let path = PageLookupResult::with_page(file);
@@ -457,7 +461,7 @@ fn main() {
     }
 
     // Initialize cache
-    let cache = Cache::new(ARCHIVE_URL, platform);
+    let cache = Cache::new(ARCHIVE_URL, args.platform);
 
     // Clear cache, pass through
     if args.clear_cache {

src/types.rs

@@ -2,10 +2,10 @@
 
 use std::{fmt, str};
 
-use serde_derive::{Deserialize, Serialize};
+use serde::Deserialize;
 
-#[derive(Debug, Eq, PartialEq, Copy, Clone, Serialize, Deserialize)]
-#[serde(rename_all = "lowercase")]
+/// The platform types supported by tldr.
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
 #[allow(dead_code)]
 pub enum PlatformType {
     Linux,
@@ -25,17 +25,58 @@ impl fmt::Display for PlatformType {
     }
 }
 
-impl str::FromStr for PlatformType {
+/// The platform lookup strategy.
+///
+/// Includes both the platform type, as well as
+#[derive(Debug, Copy, Clone)]
+pub struct PlatformStrategy {
+    /// The platform type that should be looked up.
+    pub platform_type: PlatformType,
+    /// Flag indicating whether all pages should be listed or not. This is only
+    /// used when the special platform type `all` is specified by the user.
+    pub list_all: bool,
+}
+
+impl PlatformStrategy {
+    pub fn new(platform_type: PlatformType) -> Self {
+        Self {
+            platform_type,
+            list_all: false,
+        }
+    }
+
+    /// Return a `PlatformStrategy` containing the current platform as the
+    /// target platform type.
+    pub fn current() -> Self {
+        Self {
+            platform_type: PlatformType::current(),
+            list_all: false,
+        }
+    }
+
+    /// Like `current()`, but when listing the pages, return the pages for all
+    /// platforms, not just for the current platform.
+    pub fn all() -> Self {
+        Self {
+            platform_type: PlatformType::current(),
+            list_all: true,
+        }
+    }
+}
+
+impl str::FromStr for PlatformStrategy {
     type Err = String;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match s {
-            "linux" => Ok(Self::Linux),
-            "osx" | "macos" => Ok(Self::OsX),
-            "sunos" => Ok(Self::SunOs),
-            "windows" => Ok(Self::Windows),
+            "linux" => Ok(PlatformStrategy::new(PlatformType::Linux)),
+            "osx" | "macos" => Ok(PlatformStrategy::new(PlatformType::OsX)),
+            "windows" => Ok(PlatformStrategy::new(PlatformType::Windows)),
+            "sunos" => Ok(PlatformStrategy::new(PlatformType::SunOs)),
+            "current" => Ok(PlatformStrategy::current()),
+            "all" => Ok(PlatformStrategy::all()),
             other => Err(format!(
-                "Unknown OS: {}. Possible values: linux, macos, osx, sunos, windows",
+                "Unknown platform: {}. Possible values: linux, macos, osx, windows, sunos, current, all",
                 other
             )),
         }

tests/lib.rs

@@ -523,6 +523,40 @@ fn test_list_flag_rendering() {
         .stdout("bar\nbaz\nfoo\nqux\n");
 }
 
+#[test]
+fn test_list_platform_filtering() {
+    let testenv = TestEnv::new();
+
+    testenv.add_os_entry("common", "a-common", "");
+    testenv.add_os_entry("windows", "a-windows", "");
+    testenv.add_os_entry("linux", "a-linux", "");
+    testenv.add_os_entry("linux", "b-linux", "");
+
+    // Filter: linux
+    testenv
+        .command()
+        .args(["--list", "--platform", "linux"])
+        .assert()
+        .success()
+        .stdout("a-common\na-linux\nb-linux\n");
+
+    // Filter: windows
+    testenv
+        .command()
+        .args(["--list", "--platform", "windows"])
+        .assert()
+        .success()
+        .stdout("a-common\na-windows\n");
+
+    // Filter: all
+    testenv
+        .command()
+        .args(["--list", "--platform", "all"])
+        .assert()
+        .success()
+        .stdout("a-common\na-linux\na-windows\nb-linux\n");
+}
+
 #[test]
 fn test_autoupdate_cache() {
     let testenv = TestEnv::new();