Add `capture` and `stdout` commands (#495)

This adds two new commands as a base to enable users to use the output
of scripts to do certain actions in Joshuto.

The first command this adds is a third command to start a sub-process
beside `shell` and `spawn`, called `capture`. Like `shell`, `capture` is
running blocking but unlike `shell`, it does not release the terminal
but captures the `stdout` of the sub-process and stores it in an
`AppContext` attribute.

The second command added by this commit is `stdout`. This command takes
the output from the last `capture` run, stored in the `AppContext`
attribute, and uses it for some action. The action has to be specified
as a sub-command. As of now, only `stdout cd` is implemented. This
checks that the last output of `capture` is a single line of an existing
file or directory and then changes the working directory to that.

To get significant value from these new commands, `capture` needs to be
equipped with more variables to feed more information about Joshuto's
state into external scripts, and `stdout` needs to get some more
sub-commands.

6 files changed, 58 insertions, 11 deletions

diff --git a/src/key_command/command.rs b/src/key_command/command.rs
index fad1530..0a4736f 100644
--- a/src/key_command/command.rs
+++ b/src/key_command/command.rs
@@ -3,6 +3,8 @@ use std::path;
 use crate::commands::case_sensitivity::SetType;
 use crate::commands::quit::QuitAction;
 use crate::commands::select::SelectOption;
+use crate::commands::stdout::PostProcessor;
+use crate::commands::sub_process::SubprocessCallMode;
 use crate::config::clean::app::display::line_mode::LineMode;
 use crate::config::clean::app::display::line_number::LineNumberStyle;
 use crate::config::clean::app::display::new_tab::NewTabMode;
@@ -137,7 +139,7 @@ pub enum Command {
     SetMode,
     SubProcess {
         words: Vec<String>,
-        spawn: bool,
+        mode: SubprocessCallMode,
     },
     ShowTasks,
 
@@ -181,6 +183,9 @@ pub enum Command {
     SelectFzf {
         options: SelectOption,
     },
+    StdOutPostProcess {
+        processor: PostProcessor,
+    },
     Zoxide(String),
     ZoxideInteractive,
 
diff --git a/src/key_command/constants.rs b/src/key_command/constants.rs
index 0656a58..a7d4d9a 100644
--- a/src/key_command/constants.rs
+++ b/src/key_command/constants.rs
@@ -69,8 +69,10 @@ cmd_constants![
     (CMD_SET_MODE, "set_mode"),
     (CMD_SORT, "sort"),
     (CMD_SORT_REVERSE, "sort reverse"),
-    (CMD_SUBPROCESS_FOREGROUND, "shell"),
-    (CMD_SUBPROCESS_BACKGROUND, "spawn"),
+    (CMD_SUBPROCESS_INTERACTIVE, "shell"),
+    (CMD_SUBPROCESS_SPAWN, "spawn"),
+    (CMD_SUBPROCESS_CAPTURE, "capture"),
+    (CMD_STDOUT_POST_PROCESS, "stdout"),
     (CMD_SHOW_TASKS, "show_tasks"),
     (CMD_TAB_SWITCH, "tab_switch"),
     (CMD_TAB_SWITCH_INDEX, "tab_switch_index"),
diff --git a/src/key_command/impl_appcommand.rs b/src/key_command/impl_appcommand.rs
index dd7ab84..e261391 100644
--- a/src/key_command/impl_appcommand.rs
+++ b/src/key_command/impl_appcommand.rs
@@ -1,5 +1,6 @@
 use super::constants::*;
 use super::{AppCommand, Command};
+use crate::commands::sub_process::SubprocessCallMode;
 
 impl AppCommand for Command {
     fn command(&self) -> &'static str {
@@ -85,8 +86,19 @@ impl AppCommand for Command {
             Self::FilterRegex { .. } => CMD_FILTER_REGEX,
             Self::FilterString { .. } => CMD_FILTER_STRING,
 
-            Self::SubProcess { spawn: false, .. } => CMD_SUBPROCESS_FOREGROUND,
-            Self::SubProcess { spawn: true, .. } => CMD_SUBPROCESS_BACKGROUND,
+            Self::SubProcess {
+                mode: SubprocessCallMode::Interactive,
+                ..
+            } => CMD_SUBPROCESS_INTERACTIVE,
+            Self::SubProcess {
+                mode: SubprocessCallMode::Spawn,
+                ..
+            } => CMD_SUBPROCESS_SPAWN,
+            Self::SubProcess {
+                mode: SubprocessCallMode::Capture,
+                ..
+            } => CMD_SUBPROCESS_CAPTURE,
+            Self::StdOutPostProcess { .. } => CMD_STDOUT_POST_PROCESS,
             Self::SwitchLineNums(_) => CMD_SWITCH_LINE_NUMBERS,
             Self::SetLineMode(_) => CMD_SET_LINEMODE,
 
diff --git a/src/key_command/impl_appexecute.rs b/src/key_command/impl_appexecute.rs
index c90fc2b..10ab5e9 100644
--- a/src/key_command/impl_appexecute.rs
+++ b/src/key_command/impl_appexecute.rs
@@ -1,3 +1,4 @@
+use crate::commands::stdout::post_process_std_out;
 use crate::context::AppContext;
 use crate::error::AppResult;
 use crate::ui::AppBackend;
@@ -137,9 +138,10 @@ impl AppExecute for Command {
             Self::Sort(t) => sort::set_sort(context, *t),
             Self::SetLineMode(mode) => linemode::set_linemode(context, *mode),
             Self::SortReverse => sort::toggle_reverse(context),
-            Self::SubProcess { words, spawn } => {
-                sub_process::sub_process(context, backend, words.as_slice(), *spawn)
+            Self::SubProcess { words, mode } => {
+                sub_process::sub_process(context, backend, words.as_slice(), mode.clone())
             }
+            Self::StdOutPostProcess { processor } => post_process_std_out(processor, context),
             Self::SwitchLineNums(d) => line_nums::switch_line_numbering(context, *d),
 
             Self::Flat { depth } => flat::flatten(context, *depth),
diff --git a/src/key_command/impl_comment.rs b/src/key_command/impl_comment.rs
index 0483e85..bcfd3c9 100644
--- a/src/key_command/impl_comment.rs
+++ b/src/key_command/impl_comment.rs
@@ -3,6 +3,8 @@ use crate::{
     io::FileOperationOptions,
 };
 
+use crate::commands::sub_process::SubprocessCallMode;
+
 use super::{Command, CommandComment};
 
 impl CommandComment for Command {
@@ -104,8 +106,10 @@ impl CommandComment for Command {
 
             Self::SetCaseSensitivity { .. } => "Set case sensitivity",
             Self::SetMode => "Set file permissions",
-            Self::SubProcess { spawn: false, .. } => "Run a shell command",
-            Self::SubProcess { spawn: true, .. } => "Run command in background",
+            Self::SubProcess { mode: SubprocessCallMode::Interactive, .. } => "Run a shell command (blocking) and hand over shell temporarily",
+            Self::SubProcess { mode: SubprocessCallMode::Spawn, .. } => "Spawn a shell command",
+            Self::SubProcess { mode: SubprocessCallMode::Capture, .. } => "Run a shell command (blocking), do not hand over shall but capture stdout for post-processing",
+            Self::StdOutPostProcess { .. } => "Post process stdout of last `shell` command",
             Self::ShowTasks => "Show running background tasks",
 
             Self::ToggleHiddenFiles => "Toggle hidden files displaying",
diff --git a/src/key_command/impl_from_str.rs b/src/key_command/impl_from_str.rs
index 325003f..79a7164 100644
--- a/src/key_command/impl_from_str.rs
+++ b/src/key_command/impl_from_str.rs
@@ -3,6 +3,8 @@ use std::path;
 use crate::commands::case_sensitivity::SetType;
 use crate::commands::quit::QuitAction;
 use crate::commands::select::SelectOption;
+use crate::commands::stdout::PostProcessor;
+use crate::commands::sub_process::SubprocessCallMode;
 use crate::config::clean::app::display::line_mode::LineMode;
 use crate::config::clean::app::display::line_number::LineNumberStyle;
 use crate::config::clean::app::display::new_tab::NewTabMode;
@@ -470,11 +472,22 @@ impl std::str::FromStr for Command {
                     format!("{}: {}", arg, e),
                 )),
             }
-        } else if command == CMD_SUBPROCESS_FOREGROUND || command == CMD_SUBPROCESS_BACKGROUND {
+        } else if command == CMD_SUBPROCESS_INTERACTIVE
+            || command == CMD_SUBPROCESS_SPAWN
+            || command == CMD_SUBPROCESS_CAPTURE
+        {
             match shell_words::split(arg) {
                 Ok(s) if !s.is_empty() => Ok(Self::SubProcess {
                     words: s,
-                    spawn: command == "spawn",
+                    mode: match command {
+                        CMD_SUBPROCESS_CAPTURE => SubprocessCallMode::Capture,
+                        CMD_SUBPROCESS_SPAWN => SubprocessCallMode::Spawn,
+                        CMD_SUBPROCESS_INTERACTIVE => SubprocessCallMode::Interactive,
+                        c => Err(AppError::new(
+                                AppErrorKind::InternalError,
+                                format!("Joshuto internal error: command {} unexpected in sub-process handling", c),
+                            ))?
+                    }
                 }),
                 Ok(_) => Err(AppError::new(
                     AppErrorKind::InvalidParameters,
@@ -485,6 +498,15 @@ impl std::str::FromStr for Command {
                     format!("{}: {}", arg, e),
                 )),
             }
+        } else if command == CMD_STDOUT_POST_PROCESS {
+            if let Some(processor) = PostProcessor::from_str(arg) {
+                Ok(Self::StdOutPostProcess { processor })
+            } else {
+                Err(AppError::new(
+                    AppErrorKind::InvalidParameters,
+                    format!("{} is not a valid argument for stdout post-processing", arg),
+                ))
+            }
         } else if command == CMD_SORT {
             match arg {
                 "reverse" => Ok(Self::SortReverse),