cpython/Lib/repr.py

"""Redo the `...` (representation) but with limits on most sizes."""

__all__ = ["Repr","repr"]

class Repr:
    def __init__(self):
        self.maxlevel = 6
        self.maxtuple = 6
        self.maxlist = 6
        self.maxdict = 4
        self.maxstring = 30
        self.maxlong = 40
        self.maxother = 20
    def repr(self, x):
        return self.repr1(x, self.maxlevel)
    def repr1(self, x, level):
        typename = type(x).__name__
        if ' ' in typename:
            parts = typename.split()
            typename = '_'.join(parts)
        if hasattr(self, 'repr_' + typename):
            return getattr(self, 'repr_' + typename)(x, level)
        else:
            s = `x`
            if len(s) > self.maxother:
                i = max(0, (self.maxother-3)//2)
                j = max(0, self.maxother-3-i)
                s = s[:i] + '...' + s[len(s)-j:]
            return s
    def repr_tuple(self, x, level):
        n = len(x)
        if n == 0: return '()'
        if level <= 0: return '(...)'
        s = ''
        for i in range(min(n, self.maxtuple)):
            if s: s = s + ', '
            s = s + self.repr1(x[i], level-1)
        if n > self.maxtuple: s = s + ', ...'
        elif n == 1: s = s + ','
        return '(' + s + ')'
    def repr_list(self, x, level):
        n = len(x)
        if n == 0: return '[]'
        if level <= 0: return '[...]'
        s = ''
        for i in range(min(n, self.maxlist)):
            if s: s = s + ', '
            s = s + self.repr1(x[i], level-1)
        if n > self.maxlist: s = s + ', ...'
        return '[' + s + ']'
    def repr_dict(self, x, level):
        n = len(x)
        if n == 0: return '{}'
        if level <= 0: return '{...}'
        s = ''
        keys = x.keys()
        keys.sort()
        for i in range(min(n, self.maxdict)):
            if s: s = s + ', '
            key = keys[i]
            s = s + self.repr1(key, level-1)
            s = s + ': ' + self.repr1(x[key], level-1)
        if n > self.maxdict: s = s + ', ...'
        return '{' + s + '}'
    def repr_str(self, x, level):
        s = `x[:self.maxstring]`
        if len(s) > self.maxstring:
            i = max(0, (self.maxstring-3)//2)
            j = max(0, self.maxstring-3-i)
            s = `x[:i] + x[len(x)-j:]`
            s = s[:i] + '...' + s[len(s)-j:]
        return s
    def repr_long(self, x, level):
        s = `x` # XXX Hope this isn't too slow...
        if len(s) > self.maxlong:
            i = max(0, (self.maxlong-3)//2)
            j = max(0, self.maxlong-3-i)
            s = s[:i] + '...' + s[len(s)-j:]
        return s
    def repr_instance(self, x, level):
        try:
            s = `x`
            # Bugs in x.__repr__() can cause arbitrary
            # exceptions -- then make up something
        except:
            return '<' + x.__class__.__name__ + ' instance at ' + \
                      hex(id(x))[2:] + '>'
        if len(s) > self.maxstring:
            i = max(0, (self.maxstring-3)//2)
            j = max(0, self.maxstring-3-i)
            s = s[:i] + '...' + s[len(s)-j:]
        return s

aRepr = Repr()
repr = aRepr.repr