Add Printer Font ASCII to recognised PostScript extensions (#3734)

* Register Adobe Type 1 fonts as PostScript files

* Add logic for recognising generated PFA files

* Extend list of PostScript generators

lib/linguist/generated.rb

@@ -244,7 +244,11 @@ module Linguist
     #
     # Returns true or false.
     def generated_postscript?
-      return false unless ['.ps', '.eps'].include? extname
+      return false unless ['.ps', '.eps', '.pfa'].include? extname
+
+      # Type 1 and Type 42 fonts converted to PostScript are stored as hex-encoded byte streams; these
+      # streams are always preceded the `eexec` operator (if Type 1), or the `/sfnts` key (if Type 42).
+      return true if data =~ /(\n|\r\n|\r)\s*(?:currentfile eexec\s+|\/sfnts\s+\[\1<)\h{8,}\1/
 
       # We analyze the "%%Creator:" comment, which contains the author/generator
       # of the file. If there is one, it should be in one of the first few lines.
@@ -254,10 +258,12 @@ module Linguist
       # Most generators write their version number, while human authors' or companies'
       # names don't contain numbers. So look if the line contains digits. Also
       # look for some special cases without version numbers.
-      return creator =~ /[0-9]/ ||
-        creator.include?("mpage") ||
-        creator.include?("draw") ||
-        creator.include?("ImageMagick")
+      return true if creator =~ /[0-9]|draw|mpage|ImageMagick|inkscape|MATLAB/ ||
+        creator =~ /PCBNEW|pnmtops|\(Unknown\)|Serif Affinity|Filterimage -tops/
+
+      # EAGLE doesn't include a version number when it generates PostScript.
+      # However, it does prepend its name to the document's "%%Title" field.
+      !!creator.include?("EAGLE") and lines[0..4].find {|line| line =~ /^%%Title: EAGLE Drawing /}
     end
 
     def generated_go?

lib/linguist/languages.yml

@@ -3325,6 +3325,7 @@ PostScript:
   extensions:
   - ".ps"
   - ".eps"
+  - ".pfa"
   tm_scope: source.postscript
   aliases:
   - postscr