From f1df108b31f9318611a0ea67c81682d0861cb750 Mon Sep 17 00:00:00 2001
From: Adam Schwalm <adamschwalm@gmail.com>
Date: Sun, 28 Dec 2014 17:36:31 -0600
Subject: [PATCH] Add support for multi-line strings in interpreter

---
 hy/lex/lexer.py       | 10 ++++++----
 hy/lex/parser.py      |  6 ++++++
 tests/lex/test_lex.py |  7 ++++++-
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/hy/lex/lexer.py b/hy/lex/lexer.py
index 8032fc0..5c1ba3b 100644
--- a/hy/lex/lexer.py
+++ b/hy/lex/lexer.py
@@ -42,8 +42,9 @@ lg.add('UNQUOTE', r'~%s' % end_quote)
 lg.add('HASHBANG', r'#!.*[^\r\n]')
 lg.add('HASHREADER', r'#.')
 
-
-lg.add('STRING', r'''(?x)
+# A regexp which matches incomplete strings, used to support
+# multi-line strings in the interpreter
+partial_string = r'''(?x)
     (?:u|r|ur|ru)? # prefix
     "  # start string
     (?:
@@ -53,9 +54,10 @@ lg.add('STRING', r'''(?x)
        | \\u[0-9a-fA-F]{4}  # or unicode escape
        | \\U[0-9a-fA-F]{8}  # or long unicode escape
     )* # one or more times
-    "  # end string
-''')
+'''
 
+lg.add('STRING', r'%s"' % partial_string)
+lg.add('PARTIAL_STRING', partial_string)
 
 lg.add('IDENTIFIER', r'[^()\[\]{}\'"\s;]+')
 
diff --git a/hy/lex/parser.py b/hy/lex/parser.py
index 30793f2..037a673 100644
--- a/hy/lex/parser.py
+++ b/hy/lex/parser.py
@@ -236,6 +236,12 @@ def t_string(p):
     return uni_hystring(s)
 
 
+@pg.production("string : PARTIAL_STRING")
+def t_partial_string(p):
+    # Any unterminated string requires more input
+    raise PrematureEndOfInput("Premature end of input")
+
+
 @pg.production("identifier : IDENTIFIER")
 @set_boundaries
 def t_identifier(p):
diff --git a/tests/lex/test_lex.py b/tests/lex/test_lex.py
index ebf0404..9808d70 100644
--- a/tests/lex/test_lex.py
+++ b/tests/lex/test_lex.py
@@ -49,6 +49,11 @@ def test_lex_exception():
         assert True is False
     except PrematureEndOfInput:
         pass
+    try:
+        tokenize("(foo \"bar")
+        assert True is False
+    except PrematureEndOfInput:
+        pass
 
 
 def test_unbalanced_exception():
@@ -73,7 +78,7 @@ def test_lex_expression_symbols():
 
 
 def test_lex_expression_strings():
-    """ Test that expressions can produce symbols """
+    """ Test that expressions can produce strings """
     objs = tokenize("(foo \"bar\")")
     assert objs == [HyExpression([HySymbol("foo"), HyString("bar")])]