Teach fish_indent to only indent and unindent

To be used in the following commits.

doc_src/cmds/fish_indent.rst

@@ -25,6 +25,12 @@ The following options are available:
 **-i** or **--no-indent**
     Do not indent commands; only reformat to one job per line.
 
+**--only-indent**
+    Do not reformat, only indent each line.
+
+**--only-unindent**
+    Do not reformat, only unindent each line.
+
 **-c** or **--check**
     Do not indent, only return 0 if the code is already indented as fish_indent would, the number of failed files otherwise. Also print the failed filenames if not reading from standard input.
 

share/completions/fish_indent.fish

@@ -1,6 +1,8 @@
 complete -c fish_indent -s h -l help -d 'Display help and exit'
 complete -c fish_indent -s v -l version -d 'Display version and exit'
 complete -c fish_indent -s i -l no-indent -d 'Do not indent output, only reformat into one job per line'
+complete -c fish_indent -l only-indent -d 'Do not reformat, only indent lines'
+complete -c fish_indent -l only-unindent -d 'Do not reformat, only unindent lines'
 complete -c fish_indent -l ansi -d 'Colorize the output using ANSI escape sequences'
 complete -c fish_indent -l html -d 'Output in HTML format'
 complete -c fish_indent -s w -l write -d 'Write to file'

src/bin/fish_indent.rs

@@ -36,7 +36,7 @@ use fish::highlight::{colorize, highlight_shell, HighlightRole, HighlightSpec};
 use fish::libc::setlinebuf;
 use fish::operation_context::OperationContext;
 use fish::parse_constants::{ParseTokenType, ParseTreeFlags, SourceRange};
-use fish::parse_util::parse_util_compute_indents;
+use fish::parse_util::{apply_indents, parse_util_compute_indents, SPACES_PER_INDENT};
 use fish::print_help::print_help;
 use fish::printf;
 use fish::threads;
@@ -52,10 +52,6 @@ use fish::{
     future_feature_flags,
 };
 
-// The number of spaces per indent isn't supposed to be configurable.
-// See discussion at https://github.com/fish-shell/fish-shell/pull/6790
-const SPACES_PER_INDENT: usize = 4;
-
 /// Note: this got somewhat more complicated after introducing the new AST, because that AST no
 /// longer encodes detailed lexical information (e.g. every newline). This feels more complex
 /// than necessary and would probably benefit from a more layered approach where we identify
@@ -777,6 +773,8 @@ fn throwing_main() -> i32 {
     let mut output_type = OutputType::PlainText;
     let mut output_location = L!("");
     let mut do_indent = true;
+    let mut only_indent = false;
+    let mut only_unindent = false;
     // File path for debug output.
     let mut debug_output = None;
 
@@ -795,6 +793,8 @@ fn throwing_main() -> i32 {
         ),
         wopt(L!("dump-parse-tree"), woption_argument_t::no_argument, 'P'),
         wopt(L!("no-indent"), woption_argument_t::no_argument, 'i'),
+        wopt(L!("only-indent"), woption_argument_t::no_argument, '\x04'),
+        wopt(L!("only-unindent"), woption_argument_t::no_argument, '\x05'),
         wopt(L!("help"), woption_argument_t::no_argument, 'h'),
         wopt(L!("version"), woption_argument_t::no_argument, 'v'),
         wopt(L!("write"), woption_argument_t::no_argument, 'w'),
@@ -830,6 +830,8 @@ fn throwing_main() -> i32 {
             }
             'w' => output_type = OutputType::File,
             'i' => do_indent = false,
+            '\x04' => only_indent = true,
+            '\x05' => only_unindent = true,
             '\x01' => output_type = OutputType::Html,
             '\x02' => output_type = OutputType::Ansi,
             '\x03' => output_type = OutputType::PygmentsCsv,
@@ -920,7 +922,45 @@ fn throwing_main() -> i32 {
             continue;
         }
 
-        let output_wtext = prettify(&src, do_indent);
+        let output_wtext = if only_indent || only_unindent {
+            let indents = parse_util_compute_indents(&src);
+            if only_indent {
+                apply_indents(&src, &indents)
+            } else {
+                // Only unindent.
+                let mut indented_everywhere = true;
+                for (i, c) in src.chars().enumerate() {
+                    if c != '\n' || i + 1 == src.len() {
+                        continue;
+                    }
+                    let num_spaces = SPACES_PER_INDENT * usize::try_from(indents[i + 1]).unwrap();
+                    if src.len() < i + 1 + num_spaces
+                        || !src[i + 1..].chars().take(num_spaces).all(|c| c == ' ')
+                    {
+                        indented_everywhere = false;
+                        break;
+                    }
+                }
+                if indented_everywhere {
+                    let mut out = WString::new();
+                    let mut i = 0;
+                    while i < src.len() {
+                        let c = src.as_char_slice()[i];
+                        out.push(c);
+                        i += 1;
+                        if c != '\n' || i == src.len() {
+                            continue;
+                        }
+                        i += SPACES_PER_INDENT * usize::try_from(indents[i]).unwrap();
+                    }
+                    out
+                } else {
+                    src.clone()
+                }
+            }
+        } else {
+            prettify(&src, do_indent)
+        };
 
         // Maybe colorize.
         let mut colors = vec![];

src/parse_util.rs

@@ -798,6 +798,24 @@ pub fn parse_util_compute_indents(src: &wstr) -> Vec<i32> {
     indents
 }
 
+// The number of spaces per indent isn't supposed to be configurable.
+// See discussion at https://github.com/fish-shell/fish-shell/pull/6790
+pub const SPACES_PER_INDENT: usize = 4;
+
+pub fn apply_indents(src: &wstr, indents: &[i32]) -> WString {
+    let mut indented = WString::new();
+    for (i, c) in src.chars().enumerate() {
+        indented.push(c);
+        if c != '\n' || i + 1 == src.len() {
+            continue;
+        }
+        indented.extend(
+            std::iter::repeat(' ').take(SPACES_PER_INDENT * usize::try_from(indents[i]).unwrap()),
+        );
+    }
+    indented
+}
+
 // Visit all of our nodes. When we get a job_list or case_item_list, increment indent while
 // visiting its children.
 struct IndentVisitor<'a> {
@@ -962,7 +980,12 @@ impl<'a> NodeVisitor<'a> for IndentVisitor<'a> {
 
         // If this is a leaf node, apply the current indentation.
         if node.category() == Category::leaf && range.length() != 0 {
-            self.indents[range.start()..range.end()].fill(self.indent);
+            let leading_spaces = self.src[..range.start()]
+                .chars()
+                .rev()
+                .take_while(|&c| c == ' ')
+                .count();
+            self.indents[range.start() - leading_spaces..range.end()].fill(self.indent);
             self.last_leaf_end = range.end();
             self.last_indent = self.indent;
         }

src/reader.rs

@@ -85,6 +85,7 @@ use crate::pager::{PageRendering, Pager, SelectionMotion};
 use crate::parse_constants::SourceRange;
 use crate::parse_constants::{ParseTreeFlags, ParserTestErrorBits};
 use crate::parse_tree::ParsedSource;
+use crate::parse_util::SPACES_PER_INDENT;
 use crate::parse_util::{
     parse_util_cmdsubst_extent, parse_util_compute_indents, parse_util_contains_wildcards,
     parse_util_detect_errors, parse_util_detect_errors_in_ast, parse_util_escape_string_with_quote,
@@ -2789,7 +2790,9 @@ impl ReaderData {
                         let total_offset_new = parse_util_get_offset(
                             el.text(),
                             line_new,
-                            line_offset_old - 4 * (indent_new - indent_old),
+                            line_offset_old
+                                - isize::try_from(SPACES_PER_INDENT).unwrap()
+                                    * (indent_new - indent_old),
                         );
                         self.update_buff_pos(elt, total_offset_new);
                     }

tests/checks/indent.fish

@@ -464,3 +464,35 @@ echo "
 echo this file starts late
 " | $fish_indent
 #CHECK: echo this file starts late
+
+echo 'foo|bar; begin
+echo' | $fish_indent --only-indent
+# CHECK: foo|bar; begin
+# CHECK: {{^}}    echo
+
+echo 'begin
+    echo
+end' | $fish_indent --only-unindent
+# CHECK: {{^}}begin
+# CHECK: {{^}}echo
+# CHECK: {{^}}end
+
+echo 'if true
+    begin
+        echo
+    end
+end' | $fish_indent --only-unindent
+# CHECK: {{^}}if true
+# CHECK: {{^}}begin
+# CHECK: {{^}}echo
+# CHECK: {{^}}end
+# CHECK: {{^}}end
+
+echo 'begin
+    echo
+  not indented properly
+end' | $fish_indent --only-unindent
+# CHECK: {{^}}begin
+# CHECK: {{^}}    echo
+# CHECK: {{^}}  not indented properly
+# CHECK: {{^}}end