Fix for #4804 -- escaped backslashes in interpolated strings

Part of the ongoing refinement / cleanup of the string interpolation semantics.
When scanning for an unescaped string terminator we now also allow an 0 or more
pairs of backslashes (that is, escaped backslashes) before the terminator.

Thanks to Jacob for the test I should have added.

2 files changed, 9 insertions, 1 deletions

diff --git a/lib/puppet/parser/lexer.rb b/lib/puppet/parser/lexer.rb
index a25a17e3f..9036d652e 100644
--- a/lib/puppet/parser/lexer.rb
+++ b/lib/puppet/parser/lexer.rb
@@ -520,7 +520,7 @@ class Puppet::Parser::Lexer
   def slurpstring(terminators,escapes=%w{ \\  $ ' " n t s }+["\n"],ignore_invalid_escapes=false)
     # we search for the next quote that isn't preceded by a
     # backslash; the caret is there to match empty strings
-    str = @scanner.scan_until(/([^\\]|^)[#{terminators}]/) or lex_error "Unclosed quote after '#{last}' in '#{rest}'"
+    str = @scanner.scan_until(/([^\\]|^|[^\\])([\\]{2})*[#{terminators}]/) or lex_error "Unclosed quote after '#{last}' in '#{rest}'"
     @line += str.count("\n") # literal carriage returns add to the line count.
     str.gsub!(/\\(.)/) {
       ch = $1
diff --git a/spec/unit/parser/lexer_spec.rb b/spec/unit/parser/lexer_spec.rb
index b27980bf2..2d67bf357 100755
--- a/spec/unit/parser/lexer_spec.rb
+++ b/spec/unit/parser/lexer_spec.rb
@@ -30,6 +30,14 @@ describe Puppet::Parser::Lexer do
 
       @lexer.line.should == 10
     end
+
+    it "should not think the terminator is escaped, when preceeded by an even number of backslashes" do
+      @lexer.line = 10
+      @lexer.string = "here\nis\nthe\nstring\\\\'with\nextra\njunk"
+      @lexer.slurpstring("'")
+
+      @lexer.line.should == 13
+    end
   end
 end