initial commit

1 files changed, 43 insertions, 0 deletions

diff --git a/runner.py b/runner.py
new file mode 100644
index 0000000..a2c7e99
--- /dev/null
+++ b/runner.py
@@ -0,0 +1,43 @@
+from tokens import *
+
+def std_print(arg):
+    print(arg.value)
+    #return []  # TODO this should return empty list
+    return NebLiteral(NebType.BOOL, True)
+
+std = {
+    "print": {
+        "func": NebFunction("print", [NebType.STRING], NebType.BOOL),
+        "impl": std_print }
+    }
+
+def peek(inp):
+    if len(inp) == 0:
+        return None
+    return inp[0]
+
+def evaluate(items, pop):
+    nxt = peek(items)
+    if nxt is None:
+        return pop
+    elif isinstance(nxt, NebLiteral):
+        pop = nxt.value
+        return evaluate(items[1:], pop)
+    elif isinstance(nxt, NebSymbol):
+        if not nxt.name in std:
+            raise Exception(f"no such symbol: '{nxt.name}'")
+        this_func = std[nxt.name]
+        return evaluate(items[1:], this_func["impl"])
+    elif isinstance(nxt, NebExpression):
+        if not nxt.symbol.name in std:
+            raise Exception(f"no such symbol: {nxt.symbol.name}")
+        this_func = std[nxt.symbol.name]
+        #expected_sig = " ".join(x.type_.name for x in nxt.args)
+        #if this_func["func"].in_sig() != expected_sig:
+        if this_func["func"].in_sig() != nxt.maybe_sig():
+            raise Exception(f"{nxt.symbol.name} expects '{this_func['func'].in_sig()}', got '{nxt.maybe_sig()}'")
+        ret = this_func["impl"](*(nxt.args))
+        return evaluate(items[1:], ret)
+    else:
+        raise Exception("expected a literal or an expression")
+