Implement built-in input() function.

src/runtime/builtin_modules/builtins.cpp

@@ -1012,8 +1012,31 @@ Box* rawInput(Box* prompt) {
 }
 
 Box* input(Box* prompt) {
-    fatalOrError(PyExc_NotImplementedError, "unimplemented");
-    throwCAPIException();
+    char* str;
+
+    PyObject* line = raw_input(prompt);
+    if (line == NULL)
+        throwCAPIException();
+
+    if (!PyArg_Parse(line, "s;embedded '\\0' in input line", &str))
+        throwCAPIException();
+
+    // CPython trims the string first, but our eval function takes care of that.
+    // while (*str == ' ' || *str == '\t')
+    //    str++;
+
+    Box* gbls = globals();
+    Box* lcls = locals();
+
+    // CPython has these safety checks that the builtin functions exist
+    // in the current global scope.
+    // e.g. eval('input()', {})
+    if (PyDict_GetItemString(gbls, "__builtins__") == NULL) {
+        if (PyDict_SetItemString(gbls, "__builtins__", builtins_module) != 0)
+            throwCAPIException();
+    }
+
+    return eval(line, gbls, lcls);
 }
 
 Box* builtinRound(Box* _number, Box* _ndigits) {

test/tests/input.py

+import StringIO
+import sys
+
+success_tests = ["1234",            # just a number
+                 "    123",         # whitespaces get trimmed
+                 "str(5) + \"6\""   # test for builtin function
+                ]
+special_tests = ["str(10)"]
+failure_tests = ["abcd"]
+
+orig_stdin = sys.stdin
+sio = StringIO.StringIO("\n".join(success_tests + special_tests + failure_tests))
+sys.stdin = sio
+
+for _ in success_tests:
+    print repr(input())
+
+# Special test: if the globals is empty, __builtin__ should be added to it
+# in the call to input().
+print repr(eval("input()", {}))
+
+try:
+    print repr(input())
+except NameError:
+    print "caught expected syntax error"
+
+sys.stdin = orig_stdin