basic flow control!

1 files changed, 43 insertions, 0 deletions

diff --git a/std.py b/std.py
index 1779b49..8897446 100644
--- a/std.py
+++ b/std.py
@@ -1,4 +1,5 @@
 from tokens import *
+#from runner import evaluate_expression
 import sys
 from collections import namedtuple
 
@@ -6,6 +7,7 @@ FuncImpl = namedtuple("FuncImpl", ("func", "impl"))
 
 STD = {}
 DEBUG = True
+USER = {}
 
 def _get_debug():
     return DEBUG
@@ -49,6 +51,39 @@ def std_multiply(arg1, arg2):
         typ = NebType.FLOAT
     return NebLiteral(typ, arg1.value * arg2.value)
 
+# strings
+def std_concat(arg1, arg2):
+    return NebLiteral(NebType.STRING, f"{arg1.value}{arg2.value}")
+
+# flow control
+def std_if(cond, t_branch, f_branch):
+    if cond.value:
+        ret = evaluate_expression(t_branch)
+    else:
+        ret = evaluate_expression(f_branch)
+    #return NebLiteral(NebType.BOOL, True)
+    #return NebLiteral(, True)
+    return ret
+
+def evaluate_expression(expr):
+    if not expr.symbol.name in STD:
+        raise Exception(f"no such symbol: {expr.symbol.name}")
+    this_func = STD[expr.symbol.name]
+
+    # try to match the signature
+    in_sig = expr.in_sig()
+    if in_sig in this_func:
+        ret = this_func[expr.in_sig()].impl(*(expr.args))
+        return ret
+
+    # evaluate inner expressions, if possible/necessary
+    for idx, arg in enumerate(expr.args):
+        if arg.type_ == NebType.EXPR:
+            expr.args[idx] = evaluate_expression(arg)
+            return evaluate_expression(expr)
+
+    raise Exception(f"'{expr.symbol.name}' called with unknown signature: '{expr.in_sig()}'")
+
 def build_sig_dict(*args):
     return {arg.func.in_sig(): arg for arg in args}
 
@@ -84,4 +119,12 @@ def build_std():
     multiply_float_float = FuncImpl(NebFunction("*", [NebType.FLOAT, NebType.FLOAT], NebType.FLOAT), std_multiply)
     STD["*"] = build_sig_dict(multiply_int_int, multiply_int_float, multiply_float_int, multiply_float_float)
 
+    # strings
+    concat_string_string = FuncImpl(NebFunction("concat", [NebType.STRING, NebType.STRING], NebType.STRING), std_concat)
+    STD["concat"] = build_sig_dict(concat_string_string)
+
+    # flow control
+    if_bool_expr_expr = FuncImpl(NebFunction("if", [NebType.BOOL, NebType.EXPR, NebType.EXPR], NebType.ANY), std_if)
+    STD["if"] = build_sig_dict(if_bool_expr_expr)
+
 build_std()