[oil-language] Implement 'setvar x += 1'

oil_lang/expr_eval.py

@@ -26,6 +26,20 @@ def __init__(self, mem, errfmt):
     self.mem = mem
     self.errfmt = errfmt
 
+  def ToAny(self, val):
+    """Convert to a Python object so we can calculate on it natively."""
+    if val.tag == value_e.Undef:
+      # TODO: e_die with token
+      raise NameError('undefined')
+    if val.tag == value_e.Str:
+      return val.s
+    if val.tag == value_e.StrArray:
+      return val.strs  # node: has None
+    if val.tag == value_e.AssocArray:
+      return val.d
+    if val.tag == value_e.Obj:
+      return val.obj
+
   def EvalLHS(self, node):
     if 0:
       print('EvalLHS()')
@@ -68,17 +82,7 @@ def EvalRHS(self, node):
 
     if node.tag == expr_e.Var:
       val = self.mem.GetVar(node.name.val)
-      if val.tag == value_e.Undef:
-        # TODO: e_die with token
-        raise NameError('undefined')
-      if val.tag == value_e.Str:
-        return val.s
-      if val.tag == value_e.StrArray:
-        return val.strs  # node: has None
-      if val.tag == value_e.AssocArray:
-        return val.d
-      if val.tag == value_e.Obj:
-        return val.obj
+      return self.ToAny(val)
 
     if node.tag == expr_e.DoubleQuoted:
       s = ''.join(self.EvalWordPart(part) for part in node.parts)

oil_lang/testdata/hello.osh

@@ -6,6 +6,11 @@ var x = 1 + 2*3
 
 echo "x: $x"
 
+# NOTE: we will take over 'set'
+setvar x += 1   
+
+echo "x: $x"
+
 var mylist = [1, 2, 3]
 
 var y = mylist[1] * 10
@@ -31,7 +36,18 @@ echo "str3 = $str3"
 
 
 
+#var f1 = 1.23
+#var f2 = 3.45
+
+
+
 # TODO:
-# - Mutate variables
-# - Demo dicts
+# - lexing
+#   - single-quoted strings
+#   - floats 
+# - parsing
+#   - dicts
+#   - comments at end of line
+# - eval
+#   - Mutate variables with 'setvar'
 

osh/cmd_exec.py

@@ -768,13 +768,24 @@ def _Dispatch(self, node, fork_external):
       # TODO: maybe pick out LHS and RHS here.
       # And then use mem and everything.
 
-      assert node.op.id == Id.Arith_Equal, node.op
-
       lval = self.expr_ev.EvalLHS(node.lhs)
       py_val = self.expr_ev.EvalRHS(node.rhs)
-      val = value.Obj(py_val)
-      flags = ()
-      self.mem.SetVar(lval, val, flags, scope_e.LocalOnly)
+
+      if node.op.id == Id.Arith_Equal:
+        val = value.Obj(py_val)
+        flags = ()
+        self.mem.SetVar(lval, val, flags, scope_e.LocalOnly)
+
+      elif node.op.id == Id.Arith_PlusEqual:
+        old_val = self.mem.GetVar(lval.name)
+        old_py_val = self.expr_ev.ToAny(old_val)
+
+        val = value.Obj(old_py_val + py_val)
+        flags = ()
+        self.mem.SetVar(lval, val, flags, scope_e.LocalOnly)
+
+      else:
+        raise NotImplementedError(node.op)
 
       status = 0  # TODO: what should status be?