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path: root/neb/parser.py
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from .structs import *

def parseExpression(token, prev, tokens):
    idx = 0
    args = []
    prev = token
    while tokens[idx].type_ != TokenType.CLOSE_PAREN:
        token = tokens[idx]
        inc = 1
        if token.type_ == TokenType.OPEN_PAREN:
            expr, inc = parseExpression(token, prev, tokens[idx+1:])
            args.append(expr)
        elif token.type_ in (TokenType.STRING, TokenType.TRUE, TokenType.FALSE, TokenType.INT, TokenType.FLOAT):
            expr, inc = parseLiteral(token, prev, tokens[idx+1:])
            args.append(expr)
        elif token.type_ in (TokenType.INT_TYPE, TokenType.FLOAT_TYPE, TokenType.STRING_TYPE, TokenType.ANY_TYPE, TokenType.LIST_TYPE, TokenType.NUMBER_TYPE, TokenType.BOOL_TYPE, TokenType.LITERAL_TYPE):
            expr, inc = parseType(token, prev, tokens[idx+1:])
            args.append(expr)
        else:
            expr, inc = parseSymbol(token, prev, tokens[idx+1:])
            args.append(expr)
        idx += inc
        prev = token
    
    return Expr(args), idx + 2  # parens

def parseSymbol(token, prev, tokens):
    return Symbol(token.text, token.line), 1

def parseLiteral(token, prev, tokens):
    if token.type_ == TokenType.STRING:
        return String(token.value), 1
    elif token.type_ == TokenType.INT:
        return Int(token.value), 1
    elif token.type_ == TokenType.FLOAT:
        return Float(token.value), 1
    elif token.type_ in (TokenType.TRUE, TokenType.FALSE):
        return Bool(token.value), 1
    else:
        return Literal(token.value), 1

def parseType(token, prev, tokens):
    return Type(token.text), 1

def parse(tokens):
    idx = 0
    prev = None
    exprs = []
    while tokens[idx].type_ != TokenType.EOF:
        token = tokens[idx]
        counter = 1
        if token.type_ == TokenType.OPEN_PAREN:
            expr, counter = parseExpression(token, prev, tokens[idx+1:])
            exprs.append(expr)
        elif token.type_ in (TokenType.FALSE, TokenType.TRUE, TokenType.STRING, TokenType.INT, TokenType.FLOAT):
            lit, counter = parseLiteral(token, prev, tokens[idx+1:])
            exprs.append(lit)
        elif token.type_ in (TokenType.INT_TYPE, TokenType.FLOAT_TYPE, TokenType.STRING_TYPE, TokenType.ANY_TYPE, TokenType.LIST_TYPE, TokenType.NUMBER_TYPE, TokenType.BOOL_TYPE, TokenType.LITERAL_TYPE):
            typ, counter = parseType(token, prev, tokens[idx+1:])
            exprs.append(typ)
        else:
            sym, counter = parseSymbol(token, prev, tokens[idx+1:])
            exprs.append(sym)
        
        idx += counter
        prev = token
    return exprs