grouping tokens with same first element value - pyparsing

Question

given a nested list:
(layer 0
(dielectric FR4)
(thickness 0.005)
)
(layer 1
(dielectric copper)
(thickness 0.01)
)
(layer 2
(dielectric FR4)
(thickness 0.005)
)
(physicalLayerGroup "TOP"
(minLineWidth ALWAYS_CHECK)
(maxLineWidth ALWAYS_CHECK)
(maxBondingWireLength NEVER_CHECK)
(minBondingWireLength NEVER_CHECK)
)
(physicalLayerGroup "L02"
(minLineWidth ALWAYS_CHECK)
(maxLineWidth ALWAYS_CHECK)
(maxBondingWireLength NEVER_CHECK)
(minBondingWireLength NEVER_CHECK)
)
(physicalLayerGroup "L03"
(minLineWidth ALWAYS_CHECK)
(maxLineWidth ALWAYS_CHECK)
(maxBondingWireLength NEVER_CHECK)
(minBondingWireLength NEVER_CHECK)
)
ie a list of lists where the first element of each token is identical, how can I group them? Sounds like addCondition() would fit the bill but how would one code it? Something like the following:
pp.OneOrMore( pp.Word.setName('keyy'), pp.Word.setName('valu'), pp.OneOrMore( pp.ParseResults() ).setParseAction( foo).addCondition( keyy is constant)
Any ideas?
code_warrior

Answer 1

The easiest approach, assuming that you know the names of each group, is to match for each group in turn by the expected names. Using a helper function (which I define below as outer_group) makes this easier:
text = """
(layer 0
(dielectric FR4)
(thickness 0.005)
)
... etc. ...
)"""
import pyparsing as pp
LPAR, RPAR = map(pp.Suppress, "()")
key_expr = pp.Word(pp.alphas)
qs = pp.quotedString().addParseAction(pp.removeQuotes)
val_expr = pp.pyparsing_common.number | qs | pp.Word(pp.printables, excludeChars='()')
# Dict keys need to be converted to str's
subgroup_key = val_expr().addParseAction(lambda t: str(t[0]))
subgroup = pp.Dict(pp.OneOrMore(pp.Group(LPAR + key_expr + val_expr + RPAR)))
# use this method to define each group by name
def outer_group(group_name):
lookahead = pp.FollowedBy(LPAR + pp.Suppress(group_name))
return lookahead + pp.Dict(pp.ZeroOrMore(pp.Group(LPAR
+ pp.Suppress(group_name)
+ subgroup_key
+ subgroup
+ RPAR)))(group_name)
# define groups by name as given in the posted question
# '&' operator generates an Each expression, which allows the groups to be
# parsed in any order
parser = outer_group('layer') & outer_group('physicalLayerGroup')
# how it works
data = parser.parseString(text)
print(data.dump())
print(data.layer['0'].dielectric)
print(data.physicalLayerGroup.TOP.maxLineWidth)
prints:
[[['0', ['dielectric', 'FR4'], ['thickness', 0.005]], ['1', ['dielectric', 'copper'], ['thickness', 0.01]], ['2', ['dielectric', 'FR4'], ['thickness', 0.005]]], [['TOP', ['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']], ['L02', ['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']], ['L03', ['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']]]]
- layer: [['0', ['dielectric', 'FR4'], ['thickness', 0.005]], ['1', ['dielectric', 'copper'], ['thickness', 0.01]], ['2', ['dielectric', 'FR4'], ['thickness', 0.005]]]
- 0: [['dielectric', 'FR4'], ['thickness', 0.005]]
- dielectric: 'FR4'
- thickness: 0.005
- 1: [['dielectric', 'copper'], ['thickness', 0.01]]
- dielectric: 'copper'
- thickness: 0.01
- 2: [['dielectric', 'FR4'], ['thickness', 0.005]]
- dielectric: 'FR4'
- thickness: 0.005
- physicalLayerGroup: [['TOP', ['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']], ['L02', ['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']], ['L03', ['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']]]
- L02: [['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']]
- maxBondingWireLength: 'NEVER_CHECK'
- maxLineWidth: 'ALWAYS_CHECK'
- minBondingWireLength: 'NEVER_CHECK'
- minLineWidth: 'ALWAYS_CHECK'
- L03: [['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']]
- maxBondingWireLength: 'NEVER_CHECK'
- maxLineWidth: 'ALWAYS_CHECK'
- minBondingWireLength: 'NEVER_CHECK'
- minLineWidth: 'ALWAYS_CHECK'
- TOP: [['minLineWidth', 'ALWAYS_CHECK'], ['maxLineWidth', 'ALWAYS_CHECK'], ['maxBondingWireLength', 'NEVER_CHECK'], ['minBondingWireLength', 'NEVER_CHECK']]
- maxBondingWireLength: 'NEVER_CHECK'
- maxLineWidth: 'ALWAYS_CHECK'
- minBondingWireLength: 'NEVER_CHECK'
- minLineWidth: 'ALWAYS_CHECK'
FR4
ALWAYS_CHECK
Convert parsed structure to JSON by calling asDict()
# emit JSON from parsed results
import json
print(json.dumps(data.asDict(), indent=' '))
prints:
{
"physicalLayerGroup": {
"TOP": {
"minBondingWireLength": "NEVER_CHECK",
"minLineWidth": "ALWAYS_CHECK",
"maxBondingWireLength": "NEVER_CHECK",
"maxLineWidth": "ALWAYS_CHECK"
},
"L02": {
"minBondingWireLength": "NEVER_CHECK",
"minLineWidth": "ALWAYS_CHECK",
"maxBondingWireLength": "NEVER_CHECK",
"maxLineWidth": "ALWAYS_CHECK"
},
"L03": {
"minBondingWireLength": "NEVER_CHECK",
"minLineWidth": "ALWAYS_CHECK",
"maxBondingWireLength": "NEVER_CHECK",
"maxLineWidth": "ALWAYS_CHECK"
}
},
"layer": {
"0": {
"dielectric": "FR4",
"thickness": 0.005
},
"1": {
"dielectric": "copper",
"thickness": 0.01
},
"2": {
"dielectric": "FR4",
"thickness": 0.005
}
}
}