Merge pull request #1207 from JuliaLang/special-modes

Automatically strip comment lines from special mode commands

Author: JamesWrigley

docs/src/_changelog.md

@@ -33,6 +33,17 @@ Changelog](https://keepachangelog.com).
   minor release instead of each patch release.
 - Extended the precompilation workload to cover more calls, and added a
   workaround to minimize TTFX when Revise is used ([#1210]).
+- Previously running special mode commands like `] st` would not work if the
+  cell contained comment lines:
+  ```julia
+  # Check environment
+  ] st
+  ```
+
+  Now the comment lines are stripped from special mode commands so the above
+  will work ([#1207]). Note that this only applies to *whole comment lines*, the
+  inline comments in code like `] st # check environment` will still not be
+  stripped.
 
 ## [v1.31.1] - 2025-10-20
 

src/execute_request.jl

@@ -31,6 +31,49 @@ function do_pkg_cmd(cmd::AbstractString)
     @invokelatest _do_pkg_cmd(cmd)
 end
 
+# Helper function to check if `code` is a valid special mode command. If it is,
+# then comment lines will be stripped. If it isn't, then the original `code`
+# will be returned.
+function special_mode_strip(code::String)
+    # Exit early if there are no comment or special mode characters at all
+    if !contains(code, r"#|;|\]|\?")
+        return code
+    end
+
+    # Loop over the string and look for lines that aren't comments and aren't
+    # all whitespace.
+    uncommented_line = ""
+    has_special_mode = false
+    for line in eachline(IOBuffer(code))
+        if isempty(line) || all(isspace, line)
+            continue
+        end
+
+        first_char = strip(line)[1]
+        if first_char != '#'
+            # If we've already found an uncommented line then bail out. We only
+            # support special modes with one line of commands.
+            if !isempty(uncommented_line)
+                return code
+            end
+
+            uncommented_line = line
+            has_special_mode = first_char ∈ (';', ']', '?')
+        end
+    end
+
+    if isempty(uncommented_line)
+        # If there are no uncommented lines then return the original code
+        code
+    elseif has_special_mode
+        # If there's one and it is a special mode return just that line
+        uncommented_line
+    else
+        # Otherwise return the original code
+        code
+    end
+end
+
 """
     execute_request(socket, kernel, msg)
 
@@ -60,6 +103,8 @@ function execute_request(socket, kernel, msg)
         kernel.In[kernel.n] = code
     end
 
+    code = special_mode_strip(code)
+
     # "; ..." cells are interpreted as shell commands for run
     code = replace(code, r"^\s*;.*$" =>
                    m -> string(replace(m, r"^\s*;" => "Base.repl_cmd(`"),

test/execute_request.jl

@@ -91,3 +91,45 @@ end
     @test !haskey(data, ANGRY_MIME_1)
     @test !haskey(data, ANGRY_MIME_3)
 end
+
+@testset "Special REPL mode detection" begin
+    code = "foo"
+    @test IJulia.special_mode_strip(code) == code
+    code = "foo # bar"
+    @test IJulia.special_mode_strip(code) == code
+    code = "# foo"
+    @test IJulia.special_mode_strip(code) == code
+    code = """
+    # foo
+    bar
+    """
+    @test IJulia.special_mode_strip(code) == code
+    code = """
+    foo
+    ] st
+    """
+    @test IJulia.special_mode_strip(code) == code
+
+    code = """
+    # foo
+    ] st
+    """
+    @test IJulia.special_mode_strip(code) == "] st"
+    code = """
+    # foo
+    ] st
+    ] st
+    """
+    @test IJulia.special_mode_strip(code) == code
+    code = "? foo"
+    @test IJulia.special_mode_strip(code) == code
+    code = "; foo # bar"
+    @test IJulia.special_mode_strip(code) == code
+    code = """
+     ? foo
+    # foo
+    """
+    @test IJulia.special_mode_strip(code) == " ? foo"
+    code = " ] st   "
+    @test IJulia.special_mode_strip(code) == code
+end