def merge_strings(exp):
"""merge successive strings and string-like terms into a single Str
WARNING: has side-effects
"""
# Merge all of the children first - might promote a
# Str("A") + (Str("B") + Str("C")) into an Str("A") + Str("BC")
# before we do the merge into Str("ABC")
if hasattr(exp, "expression"):
exp.expression = merge_strings(exp.expression)
elif hasattr(exp, "expressions"):
subexps = []
for subexp in exp.expressions:
subexps.append(merge_strings(subexp))
exp.expressions = subexps
if isinstance(exp, Expression.Seq):
all_strings = 1
subexps = []
for subexp in exp.expressions:
if not subexps:
subexps.append(subexp)
elif not is_mergeable(subexps[-1]):
all_strings = 0
subexps.append(subexp)
elif not is_mergeable(subexp):
all_strings = 0
subexps.append(subexp)
else:
# Previous and current are mergeable
subexps[-1] = Expression.Str(get_merge_text(subexps[-1]) + \
get_merge_text(subexp))
if all_strings and subexps:
assert len(subexps) == 1
return subexps[0]
return exp
def Str1(s):
"""(s) -> match the literal string"""
return Expression.Str(s)