10.0
10.0-rc1
10.1
10.1-rc1
11.0
11.0-rc1
11.0-rc2
11.0-rc3
11.1
11.1-rc1
11.2
11.2-rc1
11.3
11.3-rc1
12.0
12.0-rc1
12.1
12.1-rc1
6.0
6.1
6.1.1
6.3
6.4
6.5
6.6
6.7
6.8
7.0
7.1
7.2
7.3
7.4
7.5
7.5-systemd
7.6
7.6-systemd
7.7
7.7-systemd
7.8
7.8-systemd
7.9
7.9-systemd
8.0
8.1
8.2
8.3
8.4
9.0
9.1
arm
bdubbs/gcc13
ml-11.0
multilib
renodr/libudev-from-systemd
s6-init
trunk
v3_0
v3_1
v3_2
v3_3
v4_0
v4_1
v5_0
v5_1
v5_1_1
xry111/arm64
xry111/arm64-12.0
xry111/clfs-ng
xry111/lfs-next
xry111/loongarch
xry111/loongarch-12.0
xry111/loongarch-12.1
xry111/mips64el
xry111/pip3
xry111/rust-wip-20221008
xry111/update-glibc
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| 1 | <sect2>
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| 2 | <title>Contents</title>
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| 3 |
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| 4 | <para>
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| 5 | The Bison package contains the bison program.
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| 6 | </para>
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| 7 |
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| 8 | </sect2>
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| 9 |
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| 10 | <sect2><title>Description</title>
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| 11 |
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| 12 | <para>
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| 13 | Bison is a parser generator, a replacement for YACC. YACC stands for Yet
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| 14 | Another Compiler Compiler. What is Bison then? It is a program that
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| 15 | generates a program that analyzes the structure of a text file. Instead
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| 16 | of
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| 17 | writing the actual program a user specifies how things should be connected
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| 18 | and with
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| 19 | those rules a program is constructed that analyzes the text file.
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| 20 | </para>
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| 21 |
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| 22 | <para>
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| 23 | There are a lot of examples where structure is needed and one of them is
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| 24 | the
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| 25 | calculator.
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| 26 | </para>
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| 27 |
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| 28 | <para>
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| 29 | Given the string :
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| 30 | </para>
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| 31 |
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| 32 | <blockquote><literallayout>
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| 33 | 1 + 2 * 3
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| 34 | </literallayout></blockquote>
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| 35 |
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| 36 | <para>
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| 37 | A human can easily come to the result 7. Why? Because of the structure.
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| 38 | Our brain knows
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| 39 | how to interpret the string. The computer doesn't know that and Bison
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| 40 | is a
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| 41 | tool to help it understand by presenting the string in the following way
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| 42 | to the compiler:
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| 43 | </para>
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| 44 |
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| 45 | <blockquote><literallayout>
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| 46 | +
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| 47 | / \
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| 48 | * 1
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| 49 | / \
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| 50 | 2 3
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| 51 | </literallayout></blockquote>
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| 52 |
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| 53 | <para>
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| 54 | Starting at the bottom of a tree and coming across the numbers 2 and
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| 55 | 3 which are joined by the multiplication symbol, the computer
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| 56 | multiplies 2 and 3. The result of that multiplication is remembered and
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| 57 | the next thing that the computer sees is the result of 2*3 and the
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| 58 | number 1 which are joined by the add symbol. Adding 1 to the previous
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| 59 | result makes 7. In calculating the most complex calculations can be
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| 60 | broken down in this tree format and the computer just starts at the
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| 61 | bottom and works it's way up to the top and comes with the correct
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| 62 | answer. Of course, Bison isn't only used for calculators alone.
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| 63 | </para>
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| 64 |
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| 65 | </sect2>
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| 66 |
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