def parse_definition(equation_def):
"""
Parse equation definition string to create term description list.
"""
from parseEq import create_bnf
term_descs = []
bnf = create_bnf(term_descs)
try:
bnf.parseString(equation_def)
except:
raise ValueError('cannot parse equation! (%s)' % equation_def)
return term_descs
def parse_terms(regions, desc, itps):
"""
Parse equation given by 'desc' into terms. Assign each term its region.
"""
# Parse.
term_descs = []
bnf = create_bnf(term_descs, itps)
try:
bnf.parseString(desc)
except:
print "cannot parse:\n", desc
raise
# Construct terms.
terms = OneTypeList(Term)
for td in term_descs:
## print td
## pause()
try:
constructor = term_table[td.name]
except:
msg = "term '%s' is not in %s" % (td.name, sorted(term_table.keys()))
raise ValueError(msg)
region = regions[td.region]
arg_names = []
arg_steps = {}
arg_derivatives = {}
for arg in td.args:
if len(arg) == 2:
name, step = arg
derivative = None
else:
name, step = arg[1]
derivative = arg[2]
arg_names.append(name)
arg_steps[name] = step
arg_derivatives[name] = derivative
term = constructor(region, td.name, td.sign)
term.arg_names = arg_names
term.arg_steps = arg_steps
term.arg_derivatives = arg_derivatives
term.integral_name = td.integral
terms.append(term)
return terms
