provide a __signature__ function that directly returns an inspect signature to avoid going through the ast module

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/Python3Core.java

@@ -187,6 +187,7 @@ public final class Python3Core implements PythonCore {
                     "unicodedata",
                     "_locale",
                     "_sre",
+                    "function",
     };
 
     private final PythonBuiltins[] builtins;

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/function/AbstractFunctionBuiltins.java

@@ -324,15 +324,15 @@ private static Object getSignature(boolean enclosingType, Arity arity) {
             if (keywordNames.length > 0) {
                 int i = 0;
                 while (i < requiredKeywords) {
-                    sb.append(", ").append(keywordNames[i++]);
+                    sb.append(", ").append(keywordNames[i++].name).append('=');
                 }
                 if (takesVarArgs) {
                     sb.append(", *args");
                 } else {
                     sb.append(", *");
                 }
                 while (i < keywordNames.length) {
-                    sb.append(", ").append(keywordNames[i]).append("=?");
+                    sb.append(", ").append(keywordNames[i++].name).append("=?");
                 }
                 if (takesVarKeywordArgs) {
                     sb.append(", **kwargs");

graalpython/lib-graalpython/function.py

@@ -37,4 +37,35 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-# an empty file for now
+def __signature__(self):
+    import inspect
+    text_sig = self.__text_signature__
+    text_sig = text_sig[1:-1] # remove parens
+    paramnames = [p.strip() for p in text_sig.split(",")]
+    i = 0
+    kind = inspect.Parameter.POSITIONAL_ONLY
+    parameters = []
+    while i < len(paramnames):
+        p = paramnames[i]
+        if p.startswith("$"):
+            pass
+        elif p == "/":
+            kind = inspect.Parameter.POSITIONAL_OR_KEYWORD
+        elif p.startswith("**"):
+            parameters.append(inspect.Parameter(p, inspect.Parameter.VAR_KEYWORD))
+        elif p.startswith("*"):
+            kind = inspect.Parameter.KEYWORD_ONLY
+            if p != "*":
+                parameters.append(inspect.Parameter(p, inspect.Parameter.VAR_POSITIONAL))
+        else:
+            if "=" in p:
+                kind = inspect.Parameter.POSITIONAL_OR_KEYWORD
+            parameters.append(inspect.Parameter(p, kind))
+        i += 1
+
+    return inspect.Signature(parameters=parameters)
+
+
+# attach to builtin methods and builtin functions
+type(list.append).__signature__ = property(__signature__)
+type(abs).__signature__ = property(__signature__)