Description
In this homework, we are going to design a command reader “cmdReader”. It
can accept 2 kinds of inputs: standard input (keyboard) and file input (dofile). The
syntax for the executable “cmdReader” is:
cmdReader [-File
where the bold words indicate the command name or required entries, square
brackets “[ ]” indicate optional arguments, and angle brackets “< >” indicate
required arguments. An example of command line entry is:
cmdReader -File myDofile.1
Note that the option “-File” can be typed as “-file”, “-f”, “-F”, “-fi”…, etc. Do not type
the square or angle brackets.
When you specify the arguments “-File
read in commands from the doFile, and at the end of file, go to the command prompt
“cmd> ” and end the program.
Several functional keys, such as “up/down/right/left arrows”, “back space”,
“delete”, “Tab”, “Ctrl-a”, “Ctrl-e”, “Home”, “End”, “PgUp (Page Down)”, “PgDn
(Page Up)”, etc should be supported. If your keyboard does not support any of the
functional keys, use some other spare keys (e.g. Ctrl-h for Home) instead. It won’t
affect your grading. Besides, there should also be a command history array to record
the previous command entries.
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2. Keyboard Input Specification
1. Printable character (e.g. alphanumeric characters, arithmetic and logic
symbols)
When this kind of character is entered, insert it at the current cursor location.
Move the cursor to the next position on the right afterwards. For example,
inserting “k33” at the following line ( is the cursor) —
cmd> read design abcd fyyh
you will get —
cmd> read design abk33cd fyyh
2. Ctrl-a (LINE_BEGIN_KEY) or Home (HOME_KEY)
When you press “Ctrl-a” or “Home”, the cursor will move to the beginning of
the line. For example, in the following line —
cmd> read design abk33cd fyyh
pressing “ctrl-a” you will get —
cmd> read design abk33cd fyyh
3. Ctrl-e (LINE_END_KEY) or End (END_KEY)
When you press “Ctrl-e” or “End”, the cursor will move to the end of the line.
For example, in the following line —
cmd> read design abk33cd fyyh
pressing “End” you will get —
cmd> read design abk33cd fyyh
4. Backspace (ß) (BACK_SPACE_KEY)
When you press the backspace key (ß), it will delete the character before the
current cursor. The characters at and to the right of the cursor will be shifted
left for one position. For example, when the line is —
cmd> read design abk33cd fyyh
and if you press the backspace key (ß) once, it will become —
cmd> read design abk3cd fyyh
Please note that if the cursor is at the beginning of the line, pressing backspace
will not delete anything. Instead, it will produce a beep sound as an error
(calling static function “mybeep()” defined in “cmdCharDep.cpp”).
5. Delete key (DELETE_KEY)
Delete the character at the current cursor position. Afterwards, the characters
to the right of the cursor will be shifted left for one position. For example,
when the line is —
cmd> read design abk33cd fyyh
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and if you press the delete key once, it will become —
cmd> read design abk33d fyyh
Please note that if the cursor is at the end of the line, pressing delete key will
not delete anything. Instead, it will produce a beep sound as an error.
6. Tab key (TAB_KEY)
Move the cursor and the substring after the cursor right to the next “tab
position”. Insert space character(s) in between. The tab position is defined by
TAB_POSITION in “cmdParser.h”. For example, let TAB_POSITION = 8
(i.e. tab position can be 0, 8, 16… etc), when the line is —
cmd> 01234567890123456
and if you press the tab key once, it will become —
cmd> 012345 67890123456
On the other hand, if the line is —
cmd> 01234
after you press the tab key, it will become —
cmd> 01234
That is, 3 space characters will be inserted at the end.
7. Enter 8 (NEWLINE_KEY)
When the “enter” key is pressed, current line will be stored in the command
history array (i.e. “vector
cursor will move to a new line
Please note that the leading and ending “spaces” in the line will be removed
before the line is stored in the command history array. For example, after
pressing “enter” on the line —
cmd> read design abk33cd fyyh
you should store “read design abk33cd fyyh” in the command history
array.
In addition, you can press the “enter” key anywhere in the line. For example,
you will get the same string stored in the command history array for the
following two cases —
cmd> read design abk33cd fyyh
cmd> read design abk33cd fyyh
Besides, when the line is empty, or containing only space characters, pressing
“enter” key will not store anything into history array but move to a new line.
8. Up arrow # (ARROW_UP_KEY) or PgUp (PG_UP_KEY)
When the “up arrow” key is pressed, replace the current line with the previous
string stored in the command history array. When more “up arrow” keys are
pressed, you can go back to earlier stored strings. On the other hand, pressing
the “page up (PgUp)” key you will go back for PG_OFFSET lines at once
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(default PG_OFFSET = 10). If there are less than PG_OFFSET strings before
the current line in the command history array, go back to the first string in the
command history array instead. In all of the cases, the cursor will be at the end
of the line afterwards.
When you get to the top of the command history array, pressing “up arrow” or
“PgUp” key will cause a beep sound as an error and do nothing.
Note that if the current line is NOT from the command history, pressing “up
arrow” or “PgUp” key will temporarily store the current line to the end of the
command history array, without removing the leading and ending spaces. You
can always go back to this line later with “Down arrow” or “PgDn’, even if
you type in any printable key (except “enter”) to modify the history command
string. However, if you press “enter” key when browsing the history, the
temporarily stored command line will be replaced and the history command
string will be inserted to the end of the history array.
9. Down arrow $ (ARROW_DOWN_KEY) or PgDn (PG_DN_KEY)
Pressing “down arrow” or “PgDn” key allows you to traverse forward to the
newly stored strings in the command history array. The rules are similar to
those of “up arrow” and “PgUp”.
After reaching the line of currently entered string (note: may also be an empty
string), pressing “down arrow” or “PgDn” will cause a beep sound as an error.
10. Please note that what have been stored in the “CmdParser::_history”
array won’t be changed. However, if you retrieve a history string by the Up or
Down arrow, and then press the “enter” key, the history string will be stored
as a new history entry in the “_history” array. See the following examples:
[Example 10-1]
1 cmd> 1 _history: {}
2 cmd> 2 _history: { “1” }
line
history
0 cmd> 20 _history: { “1”, “2”, “” } // “” is a tmp
tmp
[Example 10-2]
1 cmd> 1 _history: {}
2 cmd> 2 _history: { “1” }
0 cmd> 20 _history: { “1”, “2”, “” } // “” is a tmp
saved
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history
[Example 10-3]
1 cmd> 1 _history: {}
2 cmd> 2 _history: { “1” }
history
0 cmd> 20 _history: { “1” }
history
11. Right arrow ” (ARROW_RIGHT_KEY)
Move the cursor right for one character. If end of the line is reached, make a
beep sound as an error.
12. Left arrow ! (ARROW_LEFT_KEY)
Move the cursor left for one character. If beginning of the line is reached,
make a beep sound as an error.
13. Any key that is not defined as above (UNDEFINED_KEY)
Making a beep sound as an error.
14. In this homework, you don’t need to handle “ESC” key, as it is part of the
input combo of the functional keys (e.g. arrow keys) and thus is difficult to be
distinguished.
15. In this homework, you don’t need to handle “line wrapping”. That is, we
assume your entered string will NOT change line. We will NOT test the
condition when the entered string is longer than the remaining spaces in the
current line.
3. Source Codes
In the “hw2” directory, there are several files:
1. main.cpp : entry of the cmdReader program. In this homework, you don’t
need to modify this file.
2. testAsc.cpp: a program to test the ASCII code of your keyboard mapping. See
Section 4 for more details. In this homework, you don’t need to modify this
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file either. However, you should play with this test program (created by “make
test”) before writing your homework.
3. cmdCharDef.h/cmdCharDef.cpp: the header file to define “enum
ParseChar” and the source code to process the supported key presses,
respectively. Please note that different shell terminals may have different
keyboard mappings, so we define two sets of keyboard mapping codes in
order to work with your and TAs’ terminals. They are separated by
“#ifndef TA_KB_SETTING” and “#else” in both files. The former part
is the one you need to fix in order to work with your terminal, and the latter
part will be used by TAs to grade your program. So please do not modify the
latter part.
4. cmdParser.h : header file to define class “CmdParser”. Please note that this
file is in “MustRemove.txt”. That is, you need to remove it from your
submission and we will use the original version (our copy) for grading.
Therefore, DO NOT customize it for any reason, as it may cause compile error
on your submission when we compile your homework.
5. cmdReader.cpp: define member functions of class “CmdParser”. In this
homework, ALL the TODO’s (except for the keyboard mapping in
“cmdCharDef.*”) are in this file.
6. Makefile: multiple objectives Makefile. Useful targets in the Makefile include:
make or make hw2: to create the main program “cmdReader”.
make test: to create the “testAsc” executable to test your keyboard setting.
make ref: using provided “cmdReader.o.ref” to create the reference program.
make linux or make mac: to create the symbolic link of “cmdReader.o.ref”
for linux or mac platform, respectively.
make clean: to clean up all the object files and the executables “cmdReader”
and “testAsc”.
make ctags: to creates the ctags for source code tracing. To trace into a
symbol, place your cursor on top of it and type “Ctrl-]”. To get back, type
“Ctrl-t”.
4. What you should do?
You are encouraged to follow the steps below for this homework assignment:
1. Read the specification (in Section 2 above) carefully and make sure you
understand the requirements.
2. THINK, before you look at the reference code and write!!! Imagine this: if
you are asked to implement this cmdReader from scratch, what will do you?
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Try to design your own data structure and program flow. Although this is
NOT part of the homework requirements, it will help you appreciate the
design of the reference code, and hopefully, you will have the capability to
design a software system in the future.
3. “make test” and you will get an executable “testAsc”. Please note that
different shell terminals may have different keyboard mappings, so you
MAY need to revise the codes in “cmdCharDef.h” and “cmdCharDef.cpp”
in order to see the correct keyboard operations of your terminal. Please refer
to the mapping below and the code in the “#else” part of “#ifndef
TA_KB_SETTING”. They are the keyboard mappings of TAs’ terminal and
TAs will use them to grade your program, so please DO NOT modify them.
Fix the codes in the “#ifndef TA_KB_SETTING” part according to the
ASCII codes responded by your testAsc program.
Ø Ctrl-a : 1
Ø Ctrl-e : 5
Ø Esc: 27
Ø Back space : 127
Ø Enter : 10
Ø Tab: 9
Ø Delete : 27 91 51 126
Ø Home: 27 91 49 126
Ø End: 27 91 52 126
Ø PgUp: 27 91 53 126
Ø PgDn: 27 91 54 126
Ø Up arrow : 27 91 65
Ø Down arrow : 27 91 66
Ø Right arrow : 27 91 67
Ø Left arrow : 27 91 68
After fixing the codes in “cmdCharDef.h” and “cmdCharDef.cpp”, you
should be able to see your keyboard mapping on the screen by “testAsc” in
the following format:
Press “Ctrl-d” to quit
27 91 65 Arrow up
27 91 68 Arrow left
27 91 49 126 Home key
1 Line begin
121 y
4 Input end
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Please note that if some of the combo keys (e.g. PgUp) do not respond, or
you really have problems making “cmdCharDef.cpp” work, use some other
key (e.g. F3, Ctrl-F, etc) as a substitution. That should not affect your
grading as TAs will use the “#else” part for compilation.
4. Type “make ref” to compile the reference program based on your
“cmdCharDef.h”, “cmdCharDef.cpp” and the provided
“cmdReader.o.ref”. You may need to type “make linux” or “make mac” in
order to choose the correct platform. Play with the reference program in
order to understand the details of the spec in this homework.
5. Study the provided source code and the brief summary in Section 3. You
then only need to finish the places marked with “TODO” in the file
“cmdReader.cpp”. You don’t need to add any new data member or
functions to it. Please try to comprehend why we define the member
functions this way. (Hint: sharing of codes)
6. Complete your coding and compile by “make” (or “make hw2”). Test your
program thoroughly. There is one test script under “hw2” called “hw2.test1”.
You can test your command reader to see whether it matches the correct
output response.
7. Rename the directory to yourID_hw2 and type “make clean” to remove
the executable and object files. Compress the directory by the command (on
Linux or Mac Terminal):
tar zcvf yourID_hw1.tgz yourID_hw1
Submit the .tgz file to Ceiba before deadline.
5. Grading
We will test your submitted program with various combinations of commands
and functional keys. Therefore, please test your program carefully before submitting it.
