language link part of evaluator

carp/src/bridge/carp.py

@@ -1,13 +1,44 @@
-import subprocess
+import re
+import time
+import diplomat
 
 
 class CarpProc:
     def __init__(self):
-        self.proc = subprocess.Popen(['carp'])
+        self.proc = diplomat.Diplomat('carp')
+        self._version_info = None
+        self.adornment_re = re.compile(".\[33m.*?\[0m")
+
+    def wait_for_boot(self):
+        while not self.proc.output():
+            time.sleep(0.5)
+        return self
+
+    def version_info(self):
+        if not self._version_info:
+            self._version_info = list(self.proc.output_stream())[0].replace("Welcome to Carp ", "")[:-1]
+        return self._version_info
+
+    def read_output(self, old_output):
+        while self.proc.output() == old_output:
+            time.sleep(0.5)
+        res = self.adornment_re.sub("", self.proc.output()[len(old_output):]).strip()
+        if res.startswith("=> "):
+            return {'result': 'success', 'value': res[3:]}
+        if not res:
+            return {'result': 'success', 'value': '()'}
+        return {'result': 'error', 'value': res}
 
     def evaluate(self, statements):
-        self.proc.stdin.send(statements)
+        assert self.proc.is_running(), "carp process has died"
+        if not self._version_info:
+            self.version_info()
+
+        old_output = self.proc.output()
+        self.proc._process.stdin.write(statements.encode("utf-8") + b"\n")
+        self.proc._process.stdin.flush()
+        return self.read_output(old_output)
 
 
 def start_carp_proc():
-    return CarpProc()
+    return CarpProc().wait_for_boot()