Add backslash escape codes - close #19

doc/user_guide.md

@@ -325,9 +325,16 @@ Regular expressions can include many special characters:
   * The `(` character begins a matching group.
   * The `{` character begins a count qualifier.
   * The `\` character escapes the following character and changes its meaning:
+    * The `\a` sequence matches an ASCII bell character (0x07).
+    * The `\b` sequence matches an ASCII backspace character (0x08).
     * The `\d` sequence matches any character `0` through `9`.
+    * The `\f` sequence matches an ASCII form feed character (0x0C).
+    * The `\n` sequence matches an ASCII new line character (0x0A).
+    * The `\r` sequence matches an ASCII carriage return character (0x0D).
     * The `\s` sequence matches a space, horizontal tab `\t`, carriage return
     `\r`, a form feed `\f`, or a vertical tab `\v` character.
+    * The `\t` sequence matches an ASCII tab character (0x09).
+    * The `\v` sequence matches an ASCII vertical tab character (0x0B).
     * Any other character matches itself.
   * The `|` character creates an alternate match.
 

lib/propane/regex.rb

@@ -134,8 +134,18 @@ class Propane
       else
         c = @pattern.slice!(0)
         case c
+        when "a"
+          CharacterRangeUnit.new("\a", "\a")
+        when "b"
+          CharacterRangeUnit.new("\b", "\b")
         when "d"
           CharacterRangeUnit.new("0", "9")
+        when "f"
+          CharacterRangeUnit.new("\f", "\f")
+        when "n"
+          CharacterRangeUnit.new("\n", "\n")
+        when "r"
+          CharacterRangeUnit.new("\r", "\r")
         when "s"
           ccu = CharacterClassUnit.new
           ccu << CharacterRangeUnit.new(" ")
@@ -145,6 +155,10 @@ class Propane
           ccu << CharacterRangeUnit.new("\f")
           ccu << CharacterRangeUnit.new("\v")
           ccu
+        when "t"
+          CharacterRangeUnit.new("\t", "\t")
+        when "v"
+          CharacterRangeUnit.new("\v", "\v")
         else
           CharacterRangeUnit.new(c)
         end

spec/propane_spec.rb

@@ -768,6 +768,89 @@ EOF
         expect(results.stderr).to eq ""
         expect(results.status).to eq 0
       end
+
+      it "matches backslash escape sequences" do
+        case language
+        when "c"
+          write_grammar <<EOF
+<<
+  #include <stdio.h>
+>>
+tokenid t;
+/\\a/ <<
+  printf("A\\n");
+>>
+/\\b/ <<
+  printf("B\\n");
+>>
+/\\t/ <<
+  printf("T\\n");
+>>
+/\\n/ <<
+  printf("N\\n");
+>>
+/\\v/ <<
+  printf("V\\n");
+>>
+/\\f/ <<
+  printf("F\\n");
+>>
+/\\r/ <<
+  printf("R\\n");
+>>
+/t/ <<
+  return $token(t);
+>>
+Start -> t;
+EOF
+        when "d"
+          write_grammar <<EOF
+<<
+  import std.stdio;
+>>
+tokenid t;
+/\\a/ <<
+  writeln("A");
+>>
+/\\b/ <<
+  writeln("B");
+>>
+/\\t/ <<
+  writeln("T");
+>>
+/\\n/ <<
+  writeln("N");
+>>
+/\\v/ <<
+  writeln("V");
+>>
+/\\f/ <<
+  writeln("F");
+>>
+/\\r/ <<
+  writeln("R");
+>>
+/t/ <<
+  return $token(t);
+>>
+Start -> t;
+EOF
+        end
+        build_parser(language: language)
+        compile("spec/test_match_backslashes.#{language}", language: language)
+        results = run
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+        verify_lines(results.stdout, [
+          "A",
+          "B",
+          "T",
+          "N",
+          "V",
+          "F",
+          "R",
+        ])
+      end
     end
   end
 end

spec/test_match_backslashes.c

@@ -0,0 +1,13 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+
+int main()
+{
+    char const * input = "\a\b\t\n\v\f\rt";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+
+    return 0;
+}

spec/test_match_backslashes.d

@@ -0,0 +1,15 @@
+import testparser;
+import std.stdio;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "\a\b\t\n\v\f\rt";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+}