Fix the examples in the dingus

examples/sqlsorta.py

@@ -0,0 +1,122 @@
+# A silly little SQL grammar. Incomplete, but you get it, right?
+from parser import *
+
+
+@rule
+def query():
+    return select_clause + opt(from_clause)
+
+
+@rule
+def select_clause():
+    return SELECT + select_column_list
+
+
+@rule(transparent=True)
+def select_column_list():
+    return alt(
+        column_spec,
+        select_column_list + COMMA + column_spec,
+    )
+
+
+@rule
+def column_spec():
+    return alt(
+        STAR,
+        expression + opt(alias),
+    )
+
+
+@rule
+def alias():
+    return AS + NAME
+
+
+@rule
+def from_clause():
+    return FROM + table_list
+
+
+@rule(transparent=True)
+def table_list():
+    return table_clause | (table_list + COMMA + table_clause)
+
+
+@rule
+def table_clause():
+    return alt(
+        table_expression + opt(alias),
+        join_clause,
+    )
+
+
+@rule
+def table_expression():
+    return alt(
+        NAME,
+        LPAREN + query + RPAREN,
+    )
+
+
+@rule
+def join_clause():
+    return join_type + table_expression + ON + expression
+
+
+@rule
+def join_type():
+    return (
+        opt(
+            alt(
+                opt(alt(LEFT, RIGHT)) + OUTER,
+                INNER,
+                CROSS,
+            )
+        )
+        + JOIN
+    )
+
+
+@rule
+def expression():
+    return NAME
+
+
+BLANKS = Terminal("BLANKS", Re.set(" ", "\t", "\r", "\n").plus())
+
+# TODO: Case insensitivity? I don't know if I care- this grammar
+#       tool is more about new languages than parsing existing ones,
+#       and this SQL grammar is just a demo. Do people want case
+#       ignoring lexers?
+SELECT = Terminal("SELECT", "select")
+AS = Terminal("AS", "as")
+COMMA = Terminal("COMMA", ",")
+STAR = Terminal("STAR", "*")
+FROM = Terminal("FROM", "from")
+WHERE = Terminal("WHERE", "where")
+LPAREN = Terminal("LPAREN", "(")
+RPAREN = Terminal("RPAREN", ")")
+
+LEFT = Terminal("LEFT", "left")
+RIGHT = Terminal("RIGHT", "right")
+OUTER = Terminal("OUTER", "outer")
+INNER = Terminal("INNER", "inner")
+CROSS = Terminal("CROSS", "cross")
+JOIN = Terminal("JOIN", "join")
+ON = Terminal("ON", "on")
+
+NAME = Terminal(
+    "NAME",
+    Re.seq(
+        Re.set(("a", "z"), ("A", "Z"), "_"),
+        Re.set(("a", "z"), ("A", "Z"), ("0", "9"), "_").star(),
+    ),
+)
+
+SQL = Grammar(
+    start=query,
+    precedence=[],
+    trivia=[BLANKS],
+    name="SQL",
+)