Port env_dispatch dependencies to rust

Either add rust wrappers for C++ functions called via ffi or port some pure code
from C++ to rust to provide support for the upcoming `env_dispatch` rewrite.

fish-rust/src/lib.rs

@@ -44,12 +44,14 @@ mod locale;
 mod nix;
 mod null_terminated_array;
 mod operation_context;
+mod output;
 mod parse_constants;
 mod parse_tree;
 mod parse_util;
 mod parser_keywords;
 mod path;
 mod re;
+mod reader;
 mod redirection;
 mod signal;
 mod smoke;

fish-rust/src/output.rs

@@ -0,0 +1,19 @@
+use bitflags::bitflags;
+
+bitflags! {
+    pub struct ColorSupport: u8 {
+        const NONE = 0;
+        const TERM_256COLOR = 1<<0;
+        const TERM_24BIT = 1<<1;
+    }
+}
+
+pub fn output_set_color_support(value: ColorSupport) {
+    extern "C" {
+        pub fn output_set_color_support(value: libc::c_int);
+    }
+
+    unsafe {
+        output_set_color_support(value.bits() as i32);
+    }
+}

fish-rust/src/reader.rs

@@ -0,0 +1,15 @@
+use crate::env::Environment;
+use crate::wchar::L;
+
+#[repr(u8)]
+pub enum CursorSelectionMode {
+    Exclusive = 0,
+    Inclusive = 1,
+}
+
+pub fn check_autosuggestion_enabled(vars: &dyn Environment) -> bool {
+    vars.get(L!("fish_autosuggestion_enabled"))
+        .map(|v| v.as_string())
+        .map(|v| v != L!("0"))
+        .unwrap_or(true)
+}

src/output.cpp

@@ -41,9 +41,10 @@ static bool term_supports_color_natively(unsigned int c) {
     return static_cast<unsigned>(max_colors) >= c + 1;
 }
 
-color_support_t output_get_color_support() { return color_support; }
-
-void output_set_color_support(color_support_t val) { color_support = val; }
+extern "C" {
+    void output_set_color_support(color_support_t val) { color_support = val; }
+    color_support_t output_get_color_support() { return color_support; }
+}
 
 unsigned char index_for_color(rgb_color_t c) {
     if (c.is_named() || !(output_get_color_support() & color_support_term256)) {

src/output.h

@@ -127,8 +127,10 @@ rgb_color_t parse_color(const env_var_t &var, bool is_background);
 /// Sets what colors are supported.
 enum { color_support_term256 = 1 << 0, color_support_term24bit = 1 << 1 };
 using color_support_t = unsigned int;
-color_support_t output_get_color_support();
-void output_set_color_support(color_support_t val);
+extern "C" {
+    color_support_t output_get_color_support();
+    void output_set_color_support(color_support_t val);
+}
 
 rgb_color_t best_color(const std::vector<rgb_color_t> &candidates, color_support_t support);
 

src/reader.cpp

@@ -2922,6 +2922,10 @@ void reader_change_cursor_selection_mode(cursor_selection_mode_t selection_mode)
     }
 }
 
+void reader_change_cursor_selection_mode(uint8_t selection_mode) {
+    reader_change_cursor_selection_mode((cursor_selection_mode_t) selection_mode);
+}
+
 static bool check_autosuggestion_enabled(const env_stack_t &vars) {
     if (auto val = vars.get(L"fish_autosuggestion_enabled")) {
         return val->as_string() != L"0";
@@ -2942,6 +2946,18 @@ void reader_set_autosuggestion_enabled(const env_stack_t &vars) {
     }
 }
 
+void reader_set_autosuggestion_enabled_ffi(bool enable) {
+    // We don't need to _change_ if we're not initialized yet.
+    reader_data_t *data = current_data_or_null();
+    if (data) {
+        if (data->conf.autosuggest_ok != enable) {
+            data->conf.autosuggest_ok = enable;
+            data->force_exec_prompt_and_repaint = true;
+            data->inputter.queue_char(readline_cmd_t::repaint);
+        }
+    }
+}
+
 /// Add a new reader to the reader stack.
 /// \return a shared pointer to it.
 static std::shared_ptr<reader_data_t> reader_push_ret(parser_t &parser,

src/reader.h

@@ -168,11 +168,17 @@ enum class cursor_selection_mode_t : uint8_t {
     inclusive,
 };
 
+#if INCLUDE_RUST_HEADERS
 void reader_change_cursor_selection_mode(cursor_selection_mode_t selection_mode);
+#else
+void reader_change_cursor_selection_mode(uint8_t selection_mode);
+#endif
 
 /// Enable or disable autosuggestions based on the associated variable.
 void reader_set_autosuggestion_enabled(const env_stack_t &vars);
 
+void reader_set_autosuggestion_enabled_ffi(bool);
+
 /// Write the title to the titlebar. This function is called just before a new application starts
 /// executing and just after it finishes.
 ///

src/screen.cpp

@@ -63,6 +63,10 @@ class scoped_buffer_t : noncopyable_t, nonmovable_t {
 // Note this is deliberately exported so that init_curses can clear it.
 layout_cache_t layout_cache_t::shared;
 
+void screen_clear_layout_cache_ffi() {
+    layout_cache_t::shared.clear();
+}
+
 /// Tests if the specified narrow character sequence is present at the specified position of the
 /// specified wide character string. All of \c seq must match, but str may be longer than seq.
 static size_t try_sequence(const char *seq, const wchar_t *str) {

src/screen.h

@@ -244,6 +244,8 @@ class screen_t {
 /// Issues an immediate clr_eos.
 void screen_force_clear_to_end();
 
+void screen_clear_layout_cache_ffi();
+
 // Information about the layout of a prompt.
 struct prompt_layout_t {
     std::vector<size_t> line_breaks;  // line breaks when rendering the prompt