1 files changed, 70 insertions, 0 deletions
diff --git a/abdl/_parser.py b/abdl/_parser.py
new file mode 100644
index 0000000..c39a45e
--- /dev/null
+++ b/abdl/_parser.py
@@ -0,0 +1,70 @@
+# This file is part of A Boneless Datastructure Language
+# Copyright (C) 2020  Soni L.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import pyparsing
+
+import abdl.exceptions
+from abdl import _vm
+
+def _build_syntax():
+    # pylint: disable=protected-access
+    from pyparsing import Suppress, Literal, Forward, CharsNotIn, StringEnd, Combine, Optional, Group, Word, srange, Empty
+
+    subtree = Forward()
+
+    skippable = Optional("?", default="")
+
+    str_literal = (Combine(Suppress("'")
+            + (Suppress("%") + ("'" | "%") | Literal("%") + (CharsNotIn("") | StringEnd()).setParseAction(abdl.exceptions.PatternError._str_escape) | CharsNotIn("%'"))[...]
+            + (Suppress("'") | StringEnd().setParseAction(abdl.exceptions.PatternError._str_end))) + skippable)
+    str_literal.setParseAction(lambda toks: [_vm.StringKey(toks)])
+
+    re_literal = (Combine(Suppress("/")
+            + (Suppress("%") + ("/" | "%") | Literal("%") + (CharsNotIn("") | StringEnd()).setParseAction(abdl.exceptions.PatternError._re_escape) | CharsNotIn("%/"))[...]
+            + (Suppress("/") | StringEnd().setParseAction(abdl.exceptions.PatternError._re_end))) + skippable)
+    re_literal.setParseAction(lambda toks: [_vm.RegexKey(toks)])
+
+    arrow = Literal("->")
+    arrow.setParseAction(lambda: [_vm.Arrow()])
+
+    identifier = Word(srange("[A-Za-z_]"), srange("[A-Za-z0-9_]"))
+    identifier.setParseAction(lambda toks: [_vm.Ident(toks)])
+
+    parameter = (Suppress("$") + skippable + identifier)
+    parameter.setParseAction(lambda toks: [_vm.Param(toks)])
+
+    type_ = (Suppress(":") + skippable + Optional(Suppress("$")) + identifier)
+    type_.setParseAction(lambda toks: [_vm.ApplyPredicate(toks)])
+
+    # support for objects-as-keys
+    keysubtree = (Suppress("[")
+            + Group(type_[...] + subtree)
+            + (Suppress("]") | (CharsNotIn("") | StringEnd()).setParseAction(abdl.exceptions.PatternError._unexpected_tok)) + skippable)
+    keysubtree.setParseAction(lambda toks: [_vm.KeySubtree(toks)])
+
+    # represents key matching - switches from "key" to "value"
+    tag = (identifier + Optional(parameter | str_literal | re_literal | keysubtree) | parameter | str_literal | re_literal | keysubtree) + type_[...] + Empty().setParseAction(lambda: [_vm.End()])
+
+    # multiple value matching
+    valuesubtree = (Suppress("(") + Group(subtree) + (Suppress(")") | CharsNotIn("").setParseAction(abdl.exceptions.PatternError._unexpected_tok) | StringEnd().setParseAction(abdl.exceptions.PatternError._unexpected_tok)) + Optional("?", default=""))
+    valuesubtree.setParseAction(lambda toks: [_vm.ValueSubtree(toks)])
+
+    # arrow and tag, value subtree
+    subtree <<= (arrow + tag)[...] + (valuesubtree + Empty().setParseAction(lambda: [_vm.End()]))[...]
+
+    return ((subtree | CharsNotIn("").setParseAction(abdl.exceptions.PatternError._unexpected_tok)) + StringEnd()).parseWithTabs()
+
+BUILT_SYNTAX = _build_syntax()