1TRIEHASH(1) User Contributed Perl Documentation TRIEHASH(1)
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6 triehash - Generate a perfect hash function derived from a trie.
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9 triehash [option] [input file]
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12 triehash takes a list of words in input file and generates a function
13 and an enumeration to describe the word
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16 The file consists of multiple lines of the form:
17 [label ~ ] word [= value]
19 This maps word to value, and generates an enumeration with entries of
21 the form:
22 label = value
24 If label is undefined, the word will be used, the minus character will
26 be replaced by an underscore. If value is undefined it is counted
27 upwards from the last value.
28 There may also be one line of the format
30 [ label ~] = value
32 Which defines the value to be used for non-existing keys. Note that
34 this also changes default value for other keys, as for normal entries.
35 So if you place
36 = 0
38 at the beginning of the file, unknown strings map to 0, and the other
40 strings map to values starting with 1. If label is not specified, the
41 default is Unknown.
42
44 -C.c file --code=.c file
45 Generate code in the given file.
46 -Hheader file --header=header file
48 Generate a header in the given file, containing a declaration of
49 the hash function and an enumeration.
50 --enum-name=word
52 The name of the enumeration.
53 --function-name=word
55 The name of the function.
56 --label-prefix=word
58 The prefix to use for labels.
59 --label-uppercase
61 Uppercase label names when normalizing them.
62 --namespace=name
64 Put the function and enum into a namespace (C++)
65 --class=name
67 Put the function and enum into a class (C++)
68 --enum-class
70 Generate an enum class instead of an enum (C++)
71 --counter-name=name
73 Use name for a counter that is set to the latest entry in the
74 enumeration + 1. This can be useful for defining array sizes.
75 --ignore-case
77 Ignore case for words.
78 --multi-byte=value
80 Generate code reading multiple bytes at once. The value is a string
81 of power of twos to enable. The default value is 320 meaning that
82 8, 4, and single byte reads are enabled. Specify 0 to disable
83 multi-byte completely, or add 2 if you also want to allow 2-byte
84 reads. 2-byte reads are disabled by default because they negatively
85 affect performance on older Intel architectures.
86 This generates code for both multiple bytes and single byte reads,
88 but only enables the multiple byte reads of GNU C compatible
89 compilers, as the following extensions are used:
90 Byte-aligned integers
92 We must be able to generate integers that are aligned to a
93 single byte using:
94 typedef uint64_t __attribute__((aligned (1))) triehash_uu64;
96 Byte-order
98 The macros __BYTE_ORDER__ and __ORDER_LITTLE_ENDIAN__ must
99 be defined.
100 We forcefully disable multi-byte reads on platforms where the
102 variable __ARM_ARCH is defined and __ARM_FEATURE_UNALIGNED is not
103 defined, as there is a measurable overhead from emulating the
104 unaligned reads on ARM.
105 --language=language
107 Generate a file in the specified language. Currently known are 'C'
108 and 'tree', the latter generating a tree.
109 --include=header
111 Add the header to the include statements of the header file. The
112 value must be surrounded by quotes or angle brackets for C code.
113 May be specified multiple times.
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116 triehash is available under the MIT/Expat license, see the source code
117 for more information.
118
120 Julian Andres Klode <jak@jak-linux.org>
121perl v5.36.0 2023-01-21 TRIEHASH(1)