# -*- coding: utf-8 -*-
#
# chemicalFormulas.py
#
# Copyright (c) 2003,2019 Paul McGuire
#

import pyparsing as pp

atomicWeight = {
    "O"  : 15.9994,
    "H"  : 1.00794,
    "Na" : 22.9897,
    "Cl" : 35.4527,
    "C"  : 12.0107,
    }

digits = "0123456789"

# Version 1
element = pp.Word(pp.alphas.upper(), pp.alphas.lower(), max=2)
# for stricter matching, use this Regex instead
# element = Regex("A[cglmrstu]|B[aehikr]?|C[adeflmorsu]?|D[bsy]|"
#                 "E[rsu]|F[emr]?|G[ade]|H[efgos]?|I[nr]?|Kr?|L[airu]|"
#                 "M[dgnot]|N[abdeiop]?|Os?|P[abdmortu]?|R[abefghnu]|"
#                 "S[bcegimnr]?|T[abcehilm]|U(u[bhopqst])?|V|W|Xe|Yb?|Z[nr]")
elementRef = pp.Group(element + pp.Optional(pp.Word(digits), default="1"))
formula = elementRef[...]

fn = lambda elemList : sum(atomicWeight[elem]*int(qty) for elem,qty in elemList)
formula.runTests("""\
    H2O
    C6H5OH
    NaCl
    """,
    fullDump=False, postParse=lambda _, tokens: "Molecular weight: {0}".format(fn(tokens)))
print()

# Version 2 - access parsed items by results name
elementRef = pp.Group(element("symbol") + pp.Optional(pp.Word(digits), default="1")("qty"))
formula = elementRef[...]

fn = lambda elemList : sum(atomicWeight[elem.symbol]*int(elem.qty) for elem in elemList)
formula.runTests("""\
    H2O
    C6H5OH
    NaCl
    """,
    fullDump=False, postParse=lambda _, tokens: "Molecular weight: {0}".format(fn(tokens)))
print()

# Version 3 - convert integers during parsing process
integer = pp.Word(digits).setParseAction(lambda t:int(t[0]))
elementRef = pp.Group(element("symbol") + pp.Optional(integer, default=1)("qty"))
formula = elementRef[...]

fn = lambda elemList : sum(atomicWeight[elem.symbol]*elem.qty for elem in elemList)
formula.runTests("""\
    H2O
    C6H5OH
    NaCl
    """,
    fullDump=False, postParse=lambda _, tokens: "Molecular weight: {0}".format(fn(tokens)))
print()

# Version 4 - parse and convert integers as subscript digits
subscript_digits = "₀₁₂₃₄₅₆₇₈₉"
subscript_int_map = dict((e[1], e[0]) for e in enumerate(subscript_digits))
def cvt_subscript_int(s):
    ret = 0
    for c in s[0]:
        ret = ret*10 + subscript_int_map[c]
    return ret
subscript_int = pp.Word(subscript_digits).addParseAction(cvt_subscript_int)

elementRef = pp.Group(element("symbol") + pp.Optional(subscript_int, default=1)("qty"))
formula = elementRef[...]
formula.runTests("""\
    H₂O
    C₆H₅OH
    NaCl
    """,
    fullDump=False, postParse=lambda _, tokens: "Molecular weight: {0}".format(fn(tokens)))
print()