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XDumper Grammar

by xmath (Hermit)
on Feb 17, 2003 at 23:37 UTC ( #236154=note: print w/replies, xml ) Need Help??


in reply to Data::XDumper

Here is a brief pseudo-grammar for XDumper's output. Note that whitespace is irrelevant and only used for clarity.
item -> var | special | label var -> ( label ':' )? classname? '<ro>'? (scalar | array | hash | glob | code | io | lvalue ) scalar -> number | string | ref | 'undef' ref -> '<weak>'? ( '\' item | '[' list? ']' | '{' hlist? '}' ) array -> '@(' list? ')' hash -> '%(' hlist? ')' list -> item (',' item)* hlist -> key '=>' item (',' key '=>' item)* glob -> '<anon>'? '*' package? name code -> '<format>'? '&(' filename ':' linenum ')' io -> '<io>' lvalue -> substr | pos | vec substr -> 'substr(' item ',' number ',' number ')' pos -> 'pos(' item ')' vec -> 'vec(' item ',' number ',' number ')' special -> '<undef>' | '<yes>' | '<no>'

In particular note that [...] is an abbreviation for \@(...) and {...} is an abbreviation for \%(...).

The abbeviated forms are used whenever possible, but sometimes it has to use the expanded form, for example when the array or hash has a prefix (blessing, read-only) or when it has a label.

For example $L001: <ro> \Foo @(1, 2) means that label $L001 names a read-only reference to a Foo-blessed array containing the numbers 1 and 2.

For people who know the perl guts: 'var', 'ref', 'array', 'hash' etc in the above grammar correspond one-to-one with SV, RV, AV, HV etc.

•Update: added format and io
•Update: added lvalues (completely forgot them earlier)

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