From 7ce0565de703ef36020f59108923da5c76d72a1e Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Sun, 10 Mar 2019 01:55:12 -0300
Subject: [PATCH] add basics of a handwritten parser

hell yeah i'm going down that path

lark made confusing stuff, i'll probably get more confused with a
handwritten one, but oh well, such is life
---
 jortsc/main.py            |  6 +--
 jortsc/parser/lexer.py    | 10 ++++-
 jortsc/parser/parser.py   |  4 +-
 jortsc/parser/syntatic.py | 91 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 105 insertions(+), 6 deletions(-)
 create mode 100644 jortsc/parser/syntatic.py

diff --git a/jortsc/main.py b/jortsc/main.py
index 46587fa..16d1ec2 100644
--- a/jortsc/main.py
+++ b/jortsc/main.py
@@ -5,7 +5,7 @@ import pprint
 import logging
 
 from jortsc.parser.lexer import lex_jorts
-from jortsc.parser.parser import parse
+from jortsc.parser.syntatic import syntatic
 
 logging.basicConfig(level=logging.DEBUG)
 
@@ -18,10 +18,10 @@ def main():
 
     tokens = lex_jorts(in_data)
     pprint.pprint(tokens)
-    print([t[0] for t in tokens])
 
-    tree = parse(in_data)
+    tree = syntatic(tokens)
     print(tree)
 
+
 if __name__ == '__main__':
     main()
diff --git a/jortsc/parser/lexer.py b/jortsc/parser/lexer.py
index 3a35a59..9405713 100644
--- a/jortsc/parser/lexer.py
+++ b/jortsc/parser/lexer.py
@@ -1,4 +1,6 @@
 import re
+
+from dataclasses import dataclass
 from enum import Enum, auto
 
 
@@ -13,6 +15,12 @@ class TokenType(Enum):
     number = auto()
 
 
+@dataclass
+class Token:
+    value: str
+    type_: TokenType
+
+
 class LexerError(Exception):
     """Lexer error."""
     pass
@@ -84,7 +92,7 @@ def lex(string: str, token_defs: list) -> list:
             pos = match.end(0)
 
             valid = True
-            tokens.append((text, tok_type))
+            tokens.append(Token(text, tok_type))
 
             # go to next token instead of checking other
             # definitions for tokens, e.g if its a reserved token
diff --git a/jortsc/parser/parser.py b/jortsc/parser/parser.py
index 47410a2..7333bd6 100644
--- a/jortsc/parser/parser.py
+++ b/jortsc/parser/parser.py
@@ -7,7 +7,7 @@ IMPORT: "import"
 COMMA: ","
 DOT: "."
 SINGLE_COMMENT: "//"
-NEWLINE: /[ \\n\\t]+/
+NEWLINE: /(\\r?\\n)+\\s*/
 ANY: /.+/
 WHITESPACE: " "
 INTEGER: /[0-9]+/
@@ -39,6 +39,6 @@ start: (NEWLINE | stmt)*
 """
 
 def parse(string: str):
-    """Parse"""
+    """Parse using Lark"""
     parser = Lark(GRAMMAR, parser='lalr', debug=True)
     return parser.parse(string)
diff --git a/jortsc/parser/syntatic.py b/jortsc/parser/syntatic.py
new file mode 100644
index 0000000..f7a3858
--- /dev/null
+++ b/jortsc/parser/syntatic.py
@@ -0,0 +1,91 @@
+from typing import Optional, Any, List
+
+from jortsc.parser.lexer import Token, TokenType
+
+
+class ParseError(Exception):
+    """Represents a parse error."""
+    pass
+
+
+class Reader:
+    """Main reader class"""
+    def __init__(self, tokens: List[Token]):
+        self.tokens = tokens
+        self.cur = 0
+
+    def next(self) -> Optional[Token]:
+        """Fetch the current token then skip to the next one."""
+        try:
+            token = self.tokens[self.cur]
+        except IndexError:
+            return None
+
+        self.cur += 1
+        return token
+
+
+def _fn_read_args(reader: Reader, cur: List = None) -> List:
+    """Recursively read the arguments of the function."""
+    if cur is None:
+        cur = []
+
+    token = reader.next()
+
+    if token.value == ')':
+        return cur
+
+    argtype, argname = reader.next(), reader.next()
+    cur.append((argtype, argname))
+    return _fn_read_args(reader, cur)
+
+
+def read_function(reader: Reader):
+    """Read a function block."""
+    token = reader.next()
+
+    if token.type_ == TokenType.whitespace:
+        pass
+    else:
+        raise ParseError('Expected whitespace')
+
+    token = reader.next()
+
+    fn_name = '_anonymous'
+    fn_args = []
+
+    if token.type_ == TokenType.identifier:
+        fn_name = token.value
+        fn_args = _fn_read_args(reader)
+        block = read_start(reader)
+    elif token.value == '(':
+        fn_args = _fn_read_args(reader)
+        block = read_start(reader)
+
+    return (fn_name, fn_args, block)
+
+
+def read_reserved(token: Token, reader: Reader):
+    """Read reserved statements."""
+    if token.value == 'fn':
+        return read_function(reader)
+
+
+def read_start(reader: Reader):
+    """Read the start of a program."""
+    token = reader.next()
+    ast = []
+    res = []
+
+    print('cur', token)
+
+    if token.type_ == TokenType.reserved:
+        res = read_reserved(token, reader)
+
+    ast.extend(res)
+    return ast
+
+
+def syntatic(tokens: List[Token]):
+    """Create an AST out of the tokens."""
+    return read_start(Reader(tokens))