py/repl: Check for an identifier char after the keyword.

- As described in the #1850.
- Add cmdline tests.

py/misc.h

@@ -123,6 +123,7 @@ bool unichar_isalpha(unichar c);
 bool unichar_isprint(unichar c);
 bool unichar_isdigit(unichar c);
 bool unichar_isxdigit(unichar c);
+bool unichar_isident(unichar c);
 bool unichar_isupper(unichar c);
 bool unichar_islower(unichar c);
 unichar unichar_tolower(unichar c);

py/repl.c

@@ -38,7 +38,7 @@ STATIC bool str_startswith_word(const char *str, const char *head) {
             return false;
         }
     }
-    return head[i] == '\0' && (str[i] == '\0' || !unichar_isalpha(str[i]));
+    return head[i] == '\0' && (str[i] == '\0' || !unichar_isident(str[i]));
 }
 
 bool mp_repl_continue_with_input(const char *input) {

py/unicode.c

@@ -145,11 +145,9 @@ bool unichar_isxdigit(unichar c) {
     return c < 128 && (attr[c] & FL_XDIGIT) != 0;
 }
 
-/*
-bool unichar_is_alpha_or_digit(unichar c) {
-    return c < 128 && (attr[c] & (FL_ALPHA | FL_DIGIT)) != 0;
+bool unichar_isident(unichar c) {
+    return c < 128 && ((attr[c] & (FL_ALPHA | FL_DIGIT)) != 0 || c == '_');
 }
-*/
 
 bool unichar_isupper(unichar c) {
     return c < 128 && (attr[c] & FL_UPPER) != 0;

tests/cmdline/repl_cont.py

@@ -29,3 +29,6 @@ def f(x):
 print(x)
 
 f(3)
+if1=1
+if1 = 2
+print(if1)

tests/cmdline/repl_cont.py.exp

@@ -50,4 +50,8 @@ two
 ...     
 >>> f(3)
 3
+>>> if1=1
+>>> if1 = 2
+>>> print(if1)
+2
 >>>