fix for when command is empty

Author: jhidding

README.md

@@ -41,6 +41,7 @@ I like to work with [Chez Scheme](https://cisco.github.io/ChezScheme/). Suppose
 
 ```yaml
 #| file: test/scheme.yml
+#| file: test/scheme.yml
 config:
   command: "scheme --eedisable"
   first_prompt: "> "
@@ -75,6 +76,7 @@ This looks very similar to the previous example:
 
 ```yaml
 #| file: test/lua.yml
+#| file: test/lua.yml
 config:
   command: "lua"
   first_prompt: "> "
@@ -116,6 +118,7 @@ The Python REPL got a revision in version 3.13, with lots of colour and ANSI cod
 
 ```yaml
 #| file: test/python.yml
+#| file: test/python.yml
 config:
   command: python -q
   first_prompt: ">>>"
@@ -141,6 +144,7 @@ The user can configure how the REPL is called and interpreted.
 
 ```python
 #| id: input-data
+#| id: input-data
 class ReplConfig(msgspec.Struct):
     """Configuration
 
@@ -173,6 +177,7 @@ Then, a session is a list of commands. Each command should be a UTF-8 string, an
 
 ```python
 #| id: input-data
+#| id: input-data
 class ReplCommand(msgspec.Struct):
     """A command to be sent to the REPL.
 

docs/index.md

@@ -6,6 +6,7 @@ The core of the implementation is handled by the `pexpect` library. We have a sm
 
 ```python
 #| id: repl-contextmanager
+#| id: repl-contextmanager
 def spawn(config: ReplConfig):
     child: pexpect.spawn[str] = pexpect.spawn(
         config.command,
@@ -36,51 +37,67 @@ def repl(config: ReplConfig) -> Generator[Callable[[str], str | None]]:
         #    child.expect(key)
         _ = child.expect(prompt)
 
-        def send(msg: str) -> str | None:
-            nonlocal prompt, continuation_prompt, change_prompt_cmd
-            lines = msg.splitlines()
-            answer: list[str] = []
+        if continuation_prompt is not None:
+            def send(msg: str) -> str | None:
+                lines = msg.splitlines()
+                answer: list[str] = []
+
+                if not lines:
+                    return None
 
-            still_waiting: bool = True
-            for line in lines:
-                logging.debug("sending: %s", line)
-                _ = child.sendline(line)
-                if continuation_prompt is not None:
+                still_waiting: bool = True
+                for line in lines:
+                    logging.debug("sending: %s", line)
+                    _ = child.sendline(line)
                     logging.debug("waiting for prompt or continuation")
                     _ = child.expect(
-                        f"(?P<cont>{continuation_prompt})|(?P<norm>{prompt})"
+                        f"(?P<norm>{prompt})|(?P<cont>{continuation_prompt})"
                     )
                     if not isinstance(child.match, re.Match):
                         continue
                     if child.match.group("cont") is not None:
-                        logging.debug("continuation")
+                        logging.debug("continuation: %s -- %s", child.before, child.after)
                         still_waiting = True
                     else:
                         logging.debug("done: %s", child.before)
                         if child.before is not None:
                             answer.append(child.before)
                         still_waiting = False
-                else:
-                    logging.debug("waiting for prompt")
+
+                if still_waiting:
+                    logging.debug(f"waiting for last prompt")
+                    # _ = child.sendline("")
                     _ = child.expect(prompt)
+                    logging.debug(f"got: %s", child.before)
                     if child.before:
                         answer.append(child.before)
-                    still_waiting = False
 
-            if still_waiting:
-                _ = child.sendline("")
+                if not answer:
+                    return None
+
+                if config.strip_ansi:
+                    ansi_escape = re.compile(r"(\u001b\[|\x1B\[)[0-?]*[ -\/]*[@-~]")
+                    return ansi_escape.sub("", answer[-1].strip())
+
+                return answer[-1].strip()
+
+        else:
+            def send(msg: str) -> str | None:
+                logging.debug("sending: %s", msg)
+
+                _ = child.sendline(msg)
                 _ = child.expect(prompt)
-                if child.before:
-                    answer.append(child.before)
 
-            if not answer:
-                return None
+                answer = child.before.strip()
+
+                if not answer:
+                    return None
 
-            if config.strip_ansi:
-                ansi_escape = re.compile(r"(\u001b\[|\x1B\[)[0-?]*[ -\/]*[@-~]")
-                return ansi_escape.sub("", answer[-1].strip())
+                if config.strip_ansi:
+                    ansi_escape = re.compile(r"(\u001b\[|\x1B\[)[0-?]*[ -\/]*[@-~]")
+                    return ansi_escape.sub("", answer)
 
-            return answer[-1].strip()
+                return answer
 
         yield send
 
@@ -91,6 +108,7 @@ We use this to run a session. The session is modified in place.
 
 ```python
 #| id: run-session
+#| id: run-session
 def run_session(session: ReplSession):
     with repl(session.config) as run:
         for cmd in session.commands:
@@ -110,6 +128,7 @@ I/O is handled by `msgspec`.
 
 ```python
 #| id: io
+#| id: io
 def read_session(port: IO[str] = sys.stdin) -> ReplSession:
     data: str = port.read()
     return msgspec.yaml.decode(data, type=ReplSession)
@@ -126,6 +145,7 @@ def write_session(session: ReplSession, port: IO[str] = sys.stdout):
 
 ```python
 #| id: imports
+#| id: imports
 # from datetime import datetime, tzinfo
 from typing import IO, cast
 from collections.abc import Generator, Callable
@@ -150,6 +170,7 @@ __version__ = importlib.metadata.version("repl-session")
 
 ```python
 #| file: src/repl_session/__init__.py
+#| file: src/repl_session/__init__.py
 """
 `repl-session` is a command-line tool to evaluate a given session
 in any REPL, and store the results.

src/repl_session/__init__.py

@@ -127,6 +127,9 @@ def send(msg: str) -> str | None:
                 lines = msg.splitlines()
                 answer: list[str] = []
 
+                if not lines:
+                    return None
+
                 still_waiting: bool = True
                 for line in lines:
                     logging.debug("sending: %s", line)