str to float cast

Author: Ehsan Totoni

hpat/_str_ext.cpp

@@ -11,6 +11,7 @@ bool str_equal(std::string* s1, std::string* s2);
 void* str_split(std::string* str, std::string* sep, int64_t *size);
 void* str_substr_int(std::string* str, int64_t index);
 int64_t str_to_int64(std::string* str);
+double str_to_float64(std::string* str);
 
 PyMODINIT_FUNC PyInit_hstr_ext(void) {
     PyObject *m;
@@ -36,6 +37,8 @@ PyMODINIT_FUNC PyInit_hstr_ext(void) {
                             PyLong_FromVoidPtr((void*)(&str_substr_int)));
     PyObject_SetAttrString(m, "str_to_int64",
                             PyLong_FromVoidPtr((void*)(&str_to_int64)));
+    PyObject_SetAttrString(m, "str_to_float64",
+                            PyLong_FromVoidPtr((void*)(&str_to_float64)));
     return m;
 }
 
@@ -103,3 +106,8 @@ int64_t str_to_int64(std::string* str)
 {
     return std::stoll(*str);
 }
+
+double str_to_float64(std::string* str)
+{
+    return std::stod(*str);
+}

hpat/str_ext.py

@@ -67,6 +67,14 @@ def generic(self, args, kws):
         if isinstance(arg, StringType):
             return signature(types.intp, arg)
 
+@infer_global(float)
+class StrToFloat(AbstractTemplate):
+    def generic(self, args, kws):
+        assert not kws
+        [arg] = args
+        if isinstance(arg, StringType):
+            return signature(types.float64, arg)
+
 import hstr_ext
 ll.add_symbol('init_string', hstr_ext.init_string)
 ll.add_symbol('init_string_const', hstr_ext.init_string_const)
@@ -76,6 +84,7 @@ def generic(self, args, kws):
 ll.add_symbol('str_split', hstr_ext.str_split)
 ll.add_symbol('str_substr_int', hstr_ext.str_substr_int)
 ll.add_symbol('str_to_int64', hstr_ext.str_to_int64)
+ll.add_symbol('str_to_float64', hstr_ext.str_to_float64)
 
 @unbox(StringType)
 def unbox_string(typ, obj, c):
@@ -162,7 +171,13 @@ def getitem_string(context, builder, sig, args):
     return (builder.call(fn, args))
 
 @lower_cast(StringType, types.int64)
-def dict_empty(context, builder, fromty, toty, val):
+def cast_str_to_int64(context, builder, fromty, toty, val):
     fnty = lir.FunctionType(lir.IntType(64), [lir.IntType(8).as_pointer()])
     fn = builder.module.get_or_insert_function(fnty, name="str_to_int64")
     return builder.call(fn, (val,))
+
+@lower_cast(StringType, types.float64)
+def cast_str_to_float64(context, builder, fromty, toty, val):
+    fnty = lir.FunctionType(lir.DoubleType(), [lir.IntType(8).as_pointer()])
+    fn = builder.module.get_or_insert_function(fnty, name="str_to_float64")
+    return builder.call(fn, (val,))

hpat/tests/test_strings.py

@@ -58,5 +58,12 @@ def test_impl(_str):
         arg = '12'
         self.assertEqual(hpat_func(arg), test_impl(arg))
 
+    def test_string_float_cast(self):
+        def test_impl(_str):
+            return float(_str)
+        hpat_func = hpat.jit(test_impl)
+        arg = '12.2'
+        self.assertEqual(hpat_func(arg), test_impl(arg))
+
 if __name__ == "__main__":
     unittest.main()