Preserve non-printing characters in show(::IO, ::TypstString)

NEWS.md

@@ -5,5 +5,7 @@
 
 ### Bug Fixes
 
+- If a `TypstString` contains any characters that satisfy `!isprint`,
+`show(::IO, ::TypstString)` now prints a format that preserves those characters.
 - Delete redundant `show_typst` documentation for `String`
 - Account for a [Typst bug with single-letter strings in `math` mode](https://github.com/typst/typst/issues/274#issue-1639854848)

docs/source/references/internals.md

@@ -29,6 +29,7 @@ Typstry.Strings.show_array
 Typstry.Strings.show_parameters
 Typstry.Strings.show_raw
 Typstry.Strings.show_vector
+Typstry.Strings.escape
 ```
 
 ### Dates.jl

src/Strings.jl

@@ -16,7 +16,6 @@ Typstry.Strings
 module Strings
 
 import Base: IOBuffer, ==, codeunit, isvalid, iterate, ncodeunits, pointer, repr, show
-using Base: escape_raw_string
 using .Docs: HTML, Text
 using .Iterators: Stateful
 using .Meta: isexpr, parse
@@ -183,7 +182,7 @@ macro typst_str(s::String)
         end
     end
 
-    current ≤ final && push!(args, s[current:final])
+    current > final || push!(args, s[current:final])
     :(TypstString(TypstText($_s)))
 end
 
@@ -475,6 +474,23 @@ show_vector(io, x) = math_mode(io, x) do io, x
     print(io, "\n", _indent ^ _depth, ")")
 end
 
+"""
+    escape(io, n)
+
+Print `\\` to `io` `n` times.
+
+# Examples
+
+```jldoctest
+julia> julia> Typstry.Strings.escape(stdout, 2)
+\\
+```
+"""
+escape(io, n) =
+    for _ in 1:n
+        print(io, '\\')
+    end
+
 ## Dates.jl
 
 """
@@ -919,9 +935,33 @@ typst"a"
 ```
 """
 function show(io::IO, ts::TypstString)
-    print(io, "typst")
-    enclose((io, text) -> escape_raw_string(io, replace(text,
-        r"(\\+)\(" => s"\1\1(")), io, ts.text, "\"")
+    text = ts.text
+
+    if all(isprint, text)
+        escapes = 0
+
+        print(io, "typst\"")
+
+        for c in text
+            if c == '\\' escapes += 1
+            else
+                if c == '\"' escape(io, escapes + 1)
+                elseif c == '(' escape(io, escapes)
+                end
+
+                escapes = 0
+            end
+
+            print(io, c)
+        end
+
+        escape(io, escapes)
+        print(io, "\"")
+    else
+        print(io, TypstString, "(", TypstText, "(")
+        show(io, text)
+        print(io, "))")
+    end
 end
 
 """

test/interface/TestStrings.jl

@@ -29,7 +29,9 @@ show_typst(io, ::X) = print(io, io[:x]::Int)
 
 const pairs = [
     typst"" => ""
-    typst"x" => "x"
+    typst"\\" => "\\" # \
+    typst"\ " => "\\ "
+    typst"\\ " => "\\\\ "
     typst"(x)" => "(x)"
     typst"𝒂(x)𝒃" => "𝒂(x)𝒃"
     typst"𝒂𝒃(x)𝒄𝒅" => "𝒂𝒃(x)𝒄𝒅"