Boolean type field attribute syntax

code/code_gen/code_gen.py

@@ -26,7 +26,7 @@ calc_grammar = """
 
     ?attr_list: attr_pair ("," attr_pair)*
 
-    ?attr_pair: NAME "=" NAME
+    ?attr_pair: NAME "=" BOOL
               | NAME "=" INT
 
     ?sum: product
@@ -71,12 +71,19 @@ calc_grammar = """
     %import common.INT
     %import common.WS
 
+    BOOL: "true" | "false"
+
     COMMENT: /#.*/
 
     %ignore COMMENT
     %ignore WS
 """
 
+def tok_to_bool(tok):
+    "Convert the value of `tok` from string to bool, while maintaining line number & column."
+    # tok.type == 'BOOL'
+    return Token.new_borrow_pos(tok.type, tok.value == "true", tok)
+
 def tok_to_int(tok):
     "Convert the value of `tok` from string to int, while maintaining line number & column."
     # tok.type == 'INT'
@@ -122,7 +129,16 @@ class VersionInfo(object):
 
 def test(terms_raw, report=False):
 
-    tree = Lark(calc_grammar, parser='lalr', lexer_callbacks = {'INT': tok_to_int}).parse(terms_raw)
+    parser = Lark(calc_grammar,
+            parser='lalr',
+            lexer_callbacks =
+            {
+            'INT': tok_to_int,
+            'BOOL': tok_to_bool
+            }
+            )
+
+    tree = parser.parse(terms_raw)
 
     ir1 = Stage1(tree)
 

code/code_gen/terms.input

@@ -10,6 +10,6 @@ nx = - ddx(c) / fsd
 ny = - ddy(c) / fsd
 nz = - ddz(c) / fsd
 
-divn (a=1, b=kill, xlow=128, xupp=320) = ddx(nx) + ddy(ny) + ddz(nz)
+divn (export=true, x0=128, x1=320) = ddx(nx) + ddy(ny) + ddz(nz)
 
 avg { c, fsd, divn }