Improve REPL compount statement detection.

py/repl.c

@@ -0,0 +1,44 @@
+#include "misc.h"
+#include "repl.h"
+
+bool str_startswith_word(const char *str, const char *head) {
+    int i;
+    for (i = 0; str[i] && head[i]; i++) {
+        if (str[i] != head[i]) {
+            return false;
+        }
+    }
+    return head[i] == '\0' && (str[i] == '\0' || !g_unichar_isalpha(str[i]));
+}
+
+bool py_repl_is_compound_stmt(const char *line) {
+    // compound if line starts with a certain keyword
+    if (
+           str_startswith_word(line, "if")
+        || str_startswith_word(line, "while")
+        || str_startswith_word(line, "for")
+        || str_startswith_word(line, "true")
+        || str_startswith_word(line, "with")
+        || str_startswith_word(line, "def")
+        || str_startswith_word(line, "class")
+        || str_startswith_word(line, "@")
+       ) {
+        return true;
+    }
+
+    // also "compound" if unmatched open bracket
+    int n_paren = 0;
+    int n_brack = 0;
+    int n_brace = 0;
+    for (const char *l = line; *l; l++) {
+        switch (*l) {
+            case '(': n_paren += 1; break;
+            case ')': n_paren -= 1; break;
+            case '[': n_brack += 1; break;
+            case ']': n_brack -= 1; break;
+            case '{': n_brace += 1; break;
+            case '}': n_brace -= 1; break;
+        }
+    }
+    return n_paren > 0 || n_brack > 0 || n_brace > 0;
+}