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basic.py

@@ -0,0 +1,223 @@
+#######################
+# CONSTANTS
+#######################
+
+DIGITS = "0123456789"
+
+#######################
+# ERRORS
+#######################
+
+class Error:
+    def __init__(self, pos_start, pos_end, error_name, details):
+        self.pos_start = pos_start
+        self.pos_end = pos_end
+        self.error_name = error_name
+        self.details = details
+
+    def as_string(self):
+        result = f'{self.error_name}: {self.details}'
+        result += f"File {self.pos_start.fn}, line {self.pos_start.ln  + 1}"
+        return result
+
+class IllegialCharError(Error):
+    def __init__(self, pos_start, pos_end, details):
+        super().__init__(pos_start, pos_end, "Illegial Character", details)
+
+#######################
+# POSITION
+#######################
+
+class Position:
+    def __init__(self, idx, ln, col, fn, ftxt):
+        self.idx = idx
+        self.ln = ln
+        self.col = col
+        self.fn = fn
+        self.ftxt = ftxt
+
+    def advance(self, current_char):
+        self.idx += 1
+        self.col += 1
+
+        if current_char == '\n':
+            self.ln += 1
+            self.col = 0
+
+        return self
+
+    def copy(self):
+        return Position(self.idx, self.ln, self.col, self.fn, self.ftxt)
+
+#######################
+# TOKENS
+#######################
+
+TT_INT     = "INT"
+TT_FLOAT   = "FLOAT"
+TT_PLUS    = "PLUS"
+TT_MINUS   = "MINUS"
+TT_MUL     = "MUL"
+TT_DIV     = "DIV"
+TT_LPAREN  = "LPAREN"
+TT_RPAREN  = "RPAREN"
+
+class Token:
+    def __init__(self, type_, value=None):
+        self.type = type_
+        self.value = value
+
+    def __repr__(self):
+        if self.value: return f"{self.type}:{self.value}"
+        return f"{self.type}"
+
+#######################
+# LEXER
+#######################
+
+class Lexer:
+    def __init__(self, fn, text):
+        self.fn = fn
+        self.text = text
+        self.pos = Position(-1, 0, -1, fn, text)
+        self.current_char = None
+        self.advance()
+
+    def advance(self):
+        self.pos.advance(self.current_char)
+        self.current_char = self.text[self.pos.idx] if self.pos.idx < len(self.text) else None
+
+    def make_tokens(self):
+        tokens = []
+
+        while self.current_char != None:
+            if self.current_char in ' \t':
+                self.advance()
+            elif self.current_char in DIGITS:
+                tokens.append(self.make_number())
+            elif self.current_char == "+":
+                tokens.append(Token(TT_PLUS))
+                self.advance()
+            elif self.current_char == "-":
+                tokens.append(Token(TT_MINUS))
+                self.advance()
+            elif self.current_char == "*":
+                tokens.append(Token(TT_MUL))
+                self.advance()
+            elif self.current_char == "/":
+                tokens.append(Token(TT_DIV))
+                self.advance()
+            elif self.current_char == "(":
+                tokens.append(Token(TT_RPAREN))
+                self.advance()
+            elif self.current_char == ")":
+                tokens.append(Token(TT_LPAREN))
+                self.advance()
+            else:
+                pos_start = self.pos.copy()
+                char = self.current_char
+                self.advance()
+                return [], IllegialCharError(pos_start, self.pos, "'" + char + "'")
+
+        return tokens, None
+
+    def make_number(self):
+        num_str = ''
+        dot_count = 0
+
+        while self.current_char != None and self.current_char in DIGITS + ".":
+            if self.current_char == '.':
+                if dot_count == 1: break
+                dot_count += 1
+                num_str += '.'
+            else:
+                num_str += self.current_char
+            self.advance()
+        if dot_count == 0:
+            return Token(TT_INT, int(num_str))
+        else:
+            return Token(TT_FLOAT, float(num_str))
+
+#######################
+# NODES
+#######################
+
+class NumberNode:
+    def __init__(self, tok):
+        self.tok = tok
+
+    def __repr__(self):
+        return f'{self.tok}'
+
+class BinOpNode:
+    def __init__(self, left_node, op_tok, right_node):
+        self.left_node = left_node
+        self.op_tok = op_tok
+        self.right_node = right_node
+
+    def __repr__(self):
+        return f'({self.left_node}, {self.op_tok}, {self.right_node})'
+
+#######################
+# PARSER
+#######################
+
+class Parser:
+    def __init__(self, tokens):
+        self.tokens = tokens
+        self.tok_idx = -1
+        self.advance()
+
+    def advance(self):
+        self.tok_idx += 1
+        if self.tok_idx < len(self.tokens):
+            self.current_tok = self.tokens[self.tok_idx]
+            return self.current_tok
+
+#########################################
+
+    def parse(self):
+        res = self.expr()
+        return res
+
+    def factor(self):
+        tok = self.current_tok
+
+        if tok.type in (TT_INT, TT_FLOAT):
+            self.advance()
+            return NumberNode(tok)
+
+    def term(self):
+        return self.bin_op(self.factor, (TT_MUL, TT_DIV))
+
+    def expr(self):
+        return self.bin_op(self.term, (TT_PLUS, TT_MINUS))
+
+#########################################
+
+    def bin_op(self, func, ops):
+        left = func()
+
+        while self.current_tok.type in ops:
+            op_tok = self.current_tok
+            self.advance()
+            right = func()
+            left = BinOpNode(left, op_tok, right)
+
+        return left
+
+#######################
+# RUN
+#######################
+
+def run(fn, text):
+    # Generate tokens
+    lexer = Lexer(fn, text)
+    tokens, error = lexer.make_tokens()
+    if error: return None, error
+
+    # Generate AST
+    parser = Parser(tokens)
+    ast = parser.parse()
+
+    return ast, None