1 files changed, 60 insertions, 0 deletions
diff --git a/compilador/parse/base.py b/compilador/parse/base.py
new file mode 100644
index 0000000..a8f6f8a
--- /dev/null
+++ b/compilador/parse/base.py
@@ -0,0 +1,60 @@
+from enum import Enum
+from tabla import LexToken, TablaLex, tokens
+from arbol import Arbol, Nodo
+from shared import Control
+from pprint import pprint
+from errors import Error
+from typing import NoReturn
+from more_itertools import seekable
+
+from tabla import TablaLex, Token
+from errors import Error
+
+class BaseParser:
+    def __init__(self, iterador: seekable):
+        self.iterador: seekable = iterador
+
+    ''' Requires the next token to have a matching ltok. Returns that
+    token, or an error. '''
+    def want(self, *want: Token) -> (LexToken | Error):
+        tok: LexToken = self.lex()
+        if len(want) == 0:
+            return tok
+        for w in want:
+            if tok.tipo == w:
+                return tok
+
+        return Error.syntax(tok.tipo, want, tok.numlinea)
+
+    ''' Looks for a matching ltok from the lexer, and if not present,
+    unlexes the token and returns void. If found, the token is
+    consumed from the lexer and is returned. '''
+    def _try(self, *want: Token) -> (LexToken | NoReturn):
+        tok: LexToken = self.lex()
+        if len(want) == 0:
+            return tok
+        for w in want:
+            if tok.tipo == w:
+                return tok
+        self.unlex()
+
+    ''' Looks for a matching ltok from the lexer, unlexes the token,
+    and returns it; or void if it was not an ltok. '''
+    def peek(self, *want: Token) -> (LexToken | NoReturn):
+        tok: LexToken = self.iterador.peek()
+        if len(want) == 0:
+            return tok
+        for w in want:
+            if tok.tipo == w:
+                return tok
+
+    def lex(self):
+        return next(self.iterador)
+
+    def unlex(self):
+        self.iterador.seek(-1)
+
+    ''' Returns a syntax error if cond is false and void otherwise '''
+    def synassert(self, cond: bool, msg: str) -> (Error | NoReturn):
+        if not cond:
+            return Error(msg = msg)