Implement Range

compiler/erg_compiler/std/_erg_std_prelude.py

@@ -1,3 +1,5 @@
+from collections.abc import Iterable, Sequence, Iterator, Container
+
 def in_operator(x, y):
     if type(y) == type:
         if isinstance(x, y):
@@ -13,3 +15,93 @@ def in_operator(x, y):
         NotImplemented
     else:
         return x in y
+
+class Range:
+    def __init__(self, start, end):
+        self.start = start
+        self.end = end
+    def __contains__(self, item):
+        pass
+    def __getitem__(self, item):
+        pass
+    def __len__(self):
+        pass
+    def __iter__(self):
+        return RangeIterator(rng=self)
+
+Sequence.register(Range)
+Container.register(Range)
+Iterable.register(Range)
+
+# represents `start<..end`
+class LeftOpenRange(Range):
+    def __contains__(self, item):
+        return self.start < item <= self.end
+    def __getitem__(self, item):
+        return NotImplemented
+    def __len__(self):
+        return NotImplemented
+
+# represents `start..<end`
+class RightOpenRange(Range):
+    def __contains__(self, item):
+        return self.start <= item < self.end
+    def __getitem__(self, item):
+        return NotImplemented
+    def __len__(self):
+        return NotImplemented
+
+# represents `start<..<end`
+class OpenRange(Range):
+    def __contains__(self, item):
+        return self.start < item < self.end
+    def __getitem__(self, item):
+        return NotImplemented
+    def __len__(self):
+        return NotImplemented
+
+# represents `start..end`
+class ClosedRange(Range):
+    def __contains__(self, item):
+        return self.start <= item <= self.end
+    def __getitem__(self, item):
+        return NotImplemented
+    def __len__(self):
+        return NotImplemented
+
+class RangeIterator:
+    def __init__(self, rng):
+        self.rng = rng
+        self.needle = self.rng.start
+        if type(self.rng.start) == int:
+            if not(self.needle in self.rng):
+                self.needle += 1
+        elif type(self.rng.start) == str:
+            if not(self.needle in self.rng):
+                self.needle = chr(ord(self.needle) + 1)
+        else:
+            if not(self.needle in self.rng):
+                self.needle = self.needle.incremented()
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if type(self.rng.start) == int:
+            if self.needle in self.rng:
+                result = self.needle
+                self.needle += 1
+                return result
+        elif type(self.rng.start) == str:
+            if self.needle in self.rng:
+                result = self.needle
+                self.needle = chr(ord(self.needle) + 1)
+                return result
+        else:
+            if self.needle in self.rng:
+                result = self.needle
+                self.needle = self.needle.incremented()
+                return result
+        raise StopIteration
+
+Iterator.register(RangeIterator)