351 lines
9.1 KiB
Plaintext
351 lines
9.1 KiB
Plaintext
# @(#)input 5.5 (Berkeley) 7/2/94
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MAPS, EXECUTABLE BUFFERS AND INPUT IN EX/VI:
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The basic rule is that input in ex/vi is a stack. Every time a key which
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gets expanded is encountered, it is expanded and the expansion is treated
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as if it were input from the user. So, maps and executable buffers are
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simply pushed onto the stack from which keys are returned. The exception
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is that if the "remap" option is turned off, only a single map expansion
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is done. I intend to be fully backward compatible with this.
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Historically, if the mode of the editor changed (ex to vi or vice versa),
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any queued input was silently discarded. I don't see any reason to either
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support or not support this semantic. I intend to retain the queued input,
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mostly because it's simpler than throwing it away.
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Historically, neither the initial command on the command line (the + flag)
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or the +cmd associated with the ex and edit commands was subject to mapping.
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Also, while the +cmd appears to be subject to "@buffer" expansion, once
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expanded it doesn't appear to work correctly. I don't see any reason to
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either support or not support these semantics, so, for consistency, I intend
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to pass both the initial command and the command associated with ex and edit
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commands through the standard mapping and @ buffer expansion.
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One other difference between the historic ex/vi and nex/nvi is that nex
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displays the executed buffers as it executes them. This means that if
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the file is:
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set term=xterm
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set term=yterm
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set term=yterm
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the user will see the following during a typical edit session:
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nex testfile
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testfile: unmodified: line 3
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:1,$yank a
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:@a
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:set term=zterm
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:set term=yterm
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:set term=xterm
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:q!
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This seems like a feature and unlikely to break anything, so I don't
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intend to match historic practice in this area.
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The rest of this document is a set of conclusions as to how I believe
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the historic maps and @ buffers work. The summary is as follows:
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1: For buffers that are cut in "line mode", or buffers that are not cut
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in line mode but which contain portions of more than a single line, a
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trailing <newline> character appears in the input for each line in the
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buffer when it is executed. For buffers not cut in line mode and which
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contain portions of only a single line, no additional characters
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appear in the input.
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2: Executable buffers that execute other buffers don't load their
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contents until they execute them.
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3: Maps and executable buffers are copied when they are executed --
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they can be modified by the command but that does not change their
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actions.
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4: Historically, executable buffers are discarded if the editor
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switches between ex and vi modes.
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5: Executable buffers inside of map commands are expanded normally.
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Maps inside of executable buffers are expanded normally.
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6: If an error is encountered while executing a mapped command or buffer,
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the rest of the mapped command/buffer is discarded. No user input
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characters are discarded.
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7: Characters in executable buffers are remapped.
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8: Characters in executable buffers are not quoted.
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Individual test cases follow. Note, in the test cases, control characters
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are not literal and will have to be replaced to make the test cases work.
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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1: For buffers that are cut in "line mode", or buffers that are not cut
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in line mode but which contain portions of more than a single line, a
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trailing <newline> character appears in the input for each line in the
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buffer when it is executed. For buffers not cut in line mode and which
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contain portions of only a single line, no additional characters
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appear in the input.
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=== test file ===
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3Gw
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w
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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=== end test file ===
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If the first line is loaded into 'a' and executed:
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1G"ayy@a
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The cursor ends up on the '2', a result of pushing "3Gw^J" onto
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the stack.
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If the first two lines are loaded into 'a' and executed:
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1G2"ayy@a
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The cursor ends up on the 'f' in "foo" in the fifth line of the
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file, a result of pushing "3Gw^Jw^J" onto the stack.
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If the first line is loaded into 'a', but not using line mode,
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and executed:
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1G"ay$@a
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The cursor ends up on the '1', a result of pushing "3Gw" onto
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the stack
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If the first two lines are loaded into 'a', but not using line mode,
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and executed:
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1G2"ay$@a
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The cursor ends up on the 'f' in "foo" in the fifth line of the
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file, a result of pushing "3Gw^Jw^J" onto the stack.
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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2: Executable buffers that execute other buffers don't load their
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contents until they execute them.
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=== test file ===
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cwLOAD B^[
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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@a@b
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"byy
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=== end test file ===
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The command is loaded into 'e', and then executed. 'e' executes
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'a', which loads 'b', then 'e' executes 'b'.
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5G"eyy6G"ayy1G@e
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The output should be:
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=== output file ===
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cwLOAD B^[
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LOAD B 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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@a@b
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"byy
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=== end output file ===
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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3: Maps and executable buffers are copied when they are executed --
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they can be modified by the command but that does not change their
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actions.
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Executable buffers:
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=== test file ===
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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@a@b
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"eyy
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cwEXECUTE B^[
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=== end test file ===
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4G"eyy5G"ayy6G"byy1G@eG"ep
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The command is loaded into 'e', and then executed. 'e' executes
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'a', which loads 'e', then 'e' executes 'b' anyway.
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The output should be:
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=== output file ===
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line 1 foo bar baz
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EXECUTE B 2 foo bar baz
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line 3 foo bar baz
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@a@b
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"eyy
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cwEXECUTE B^[
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line 1 foo bar baz
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=== end output file ===
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Maps:
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=== test file ===
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Cine 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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=== end test file ===
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Entering the command ':map = :map = rB^V^MrA^M1G==' shows that
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the first time the '=' is entered the '=' map is set and the
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character is changed to 'A', the second time the character is
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changed to 'B'.
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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4: Historically, executable buffers are discarded if the editor
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switches between ex and vi modes.
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=== test file ===
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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cwCHANGE^[Q:set
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set|visual|1Gwww
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=== end test file ===
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vi testfile
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4G"ayy@a
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ex testfile
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$p
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yank a
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@a
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In vi, the command is loaded into 'a' and then executed. The command
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subsequent to the 'Q' is (historically, silently) discarded.
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In ex, the command is loaded into 'a' and then executed. The command
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subsequent to the 'visual' is (historically, silently) discarded. The
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first set command is output by ex, although refreshing the screen usually
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causes it not to be seen.
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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5: Executable buffers inside of map commands are expanded normally.
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Maps inside of executable buffers are expanded normally.
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Buffers inside of map commands:
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=== test file ===
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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cwREPLACE BY A^[
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=== end test file ===
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4G"ay$:map x @a
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1Gx
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The output should be:
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=== output file ===
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REPLACE BY A 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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cwREPLACE BY A^[
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=== end output file ===
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Maps commands inside of executable buffers:
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=== test file ===
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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X
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=== end test file ===
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:map X cwREPLACE BY XMAP^[
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4G"ay$1G@a
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The output should be:
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=== output file ===
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REPLACE BY XMAP 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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X
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=== end output file ===
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Here's a test that does both, repeatedly.
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=== test file ===
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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X
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Y
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cwREPLACED BY C^[
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blank line
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=== end test file ===
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:map x @a
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4G"ay$
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:map X @b
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5G"by$
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:map Y @c
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6G"cy$
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1Gx
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The output should be:
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=== output file ===
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REPLACED BY C 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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X
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Y
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cwREPLACED BY C^[
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blank line
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=== end output file ===
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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6: If an error is encountered while executing a mapped command or
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a buffer, the rest of the mapped command/buffer is discarded. No
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user input characters are discarded.
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=== test file ===
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line 1 foo bar baz
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line 2 foo bar baz
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line 3 foo bar baz
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:map = 10GcwREPLACMENT^V^[^[
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=== end test file ===
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The above mapping fails, however, if the 10G is changed to 1, 2,
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or 3G, it will succeed.
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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7: Characters in executable buffers are remapped.
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=== test file ===
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abcdefghijklmnnop
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ggg
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=== end test file ===
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:map g x
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2G"ay$1G@a
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The output should be:
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=== output file ===
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defghijklmnnop
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ggg
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=== end output file ===
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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8: Characters in executable buffers are not quoted.
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=== test file ===
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iFOO^[
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=== end test file ===
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1G"ay$2G@a
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The output should be:
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=== output file ===
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iFOO^[
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FOO
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=== end output file ===
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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