sexpr.py

# to print an s-expression
#
# e.g.
# (macro-definition
#   (id-expression name)
#   (statements
#     (...)
#     (...)
#     (...)))
#
# 1. Print opening bracket
# 2. Print first item in list directly
# 3. If the list contains any lists or the length condition holds
#    a. Increment the indentation level
#    b. For each item in the list:
#       i.   Print a newline
#       ii.  Print enough spaces to reach the current indentation level
#       iii. Print the sub-expression
# 4. Otherwise
#    a. For each item in the list:
#       i.  Print a space
#       ii. Print the sub-expression *without considering the first branch of the if*
# 5. Print a closing bracket
#
# (Without the restriction on considering the first branch of the if, this is exponential complexity)

def to_sexpr(o, indent=None):
    return fmt_sexpr(json.loads(MyJSONEncoder().encode(o)))

def fmt_sexpr(o, depth=1):
    if isinstance(o, dict):
        return fmt_sexpr(list(o.values()), depth)
    if isinstance(o, tuple):
        return fmt_sexpr(list(o), depth)
    if isinstance(o, list):
        if len(o) == 0:
            return '()'
        if len(o) == 1:
            return fmt_sexpr(o[0], depth)
        return fmt_sexpr_list(o, depth)
    return str(o)

def fmt_sexpr_short(o, depth=1):
    if isinstance(o, dict):
        return fmt_sexpr_short(list(o.values()))
    if isinstance(o, tuple):
        return fmt_sexpr_short(list(o))
    if isinstance(o, list):
        if len(o) == 0:
            return '()'
        if len(o) == 1:
            return fmt_sexpr_short(o[0])
        return fmt_sexpr_list_short(o)
    return str(o)

@compose(''.join)
def fmt_sexpr_list_long(o, depth):
    yield '('
    yield fmt_sexpr(o[0], depth + 1)
    for item in o[1:]:
        yield '\n'
        yield (2 * depth * ' ')
        yield fmt_sexpr(item, depth + 1)
    yield ')'

@compose(''.join)
def fmt_sexpr_list_short(o):
    yield '('
    yield fmt_sexpr_short(o[0])
    for item in o[1:]:
        yield ' '
        yield fmt_sexpr_short(item)
    yield ')'

def fmt_sexpr_list(o, depth):
    result = fmt_sexpr_list_short(o)
    if max(map(len, result.splitlines())) > 80:
        return fmt_sexpr_list_long(o, depth)
    return result