EE3011 Homework #3 solved


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In this homework, we are going to design a more complete user interface (on top
of Homework #2) for a simple command-line database system (somewhat similar to
Homework #1). The generated executable is called “mydb” and has the following
mydb [-File ]
where the bold words indicate the command name or required entries, square
brackets “[ ]” indicate optional arguments, and angle brackets “< >” indicate
required arguments. Do not type the square or angle brackets.
This simple command-line database system should provide the following
1. Create DB by reading in data from a .json (JSON) file. Please refer to
Homework #1 for the simplified JSON format. However, we further limit the
format of the “key” to a string starting with either English letters (i.e. a-z, AZ) or underline symbol (i.e. ‘_’). (See command “DBAPpend” for more
detailed description)
2. Add a new JSON element to the end of the JSON object.
3. Print out the JSON object or a JSON element in the JSON object by
specifying a “key” string.
4. Sort the JSON elements by either “key” or “value” in ascending order.
5. Report the number of JSON elements in the JSON object.
6. Compute the summation and average of the JSON elements by their “values”.
7. Report the maximum and minimum JSON element by comparing the
8. Use “cout” to print the correct outputs and “cerrr” to print out the erroneous
2. Supported Commands
The supported commands of “mydb” include:
DBAPpend: append a JSON element (key-value
pair(s)) to the end of DB
DBAVerage: compute the average of the DB
DBCount: report the number of JSON elements in
the DB
DBMAx: report the maximum JSON element
DBMIn: report the minimum JSON element
DBPrint: print the JSON element(s) in the DB
DBRead: read data from .csv file
DBSOrt: sort the JSON object by key or value
DBSUm: compute the summation of the DB
DOfile: execute the commands in the dofile
HELp: print this help message
HIStory: print command history
Quit: quit the execution
The lexicographic notations in this section are summarized in the following table:
or leading ‘-‘ The leading ‘-‘ and capital letters in the command name or
parameters are mandatory entries and will be compared “caseinsensitively”. The following letters can be partially skipped.
However, when entered, they should match the specification
For example, for the command “DOfile” —
l do (ok)
l dofile (ok)
l DoF (ok)
l d (not ok; at least “do”)
l dofill (not ok; not match)
l dofile1 (not ok; extra letter)
Round bracket “()” Meaning it should be replaced by a proper argument as
suggested by the “(type variable)” description in the round
brackets. For example, the parameter in “HIStory [(int
nPrint)]” should be replaced by an integer which is the number
of histories to print.
Angle brackets
Mandatory parameters; they should appear in the same relative
order as specified in the command usage.
Square brackets “[]” Optional parameters; they can appear anywhere in the
command parameters.
Dot dot dot “…” Repeatable arguments; meaning the followed argument can be
repeated multiple times.
Or ‘|’ Or condition; either one of the argument will do.
Please note that the “[ ]” optional parameters can appear anywhere in the
command line, while the “< >” mandatory parameters must follow the relative order
as specified in the command usage. For example, if the command “test” has the
following usage —
Usage: TEST [op3] [op4]
The following are legal:
> test op1 op2 // op3 or op4 can be omitted
> test op4 op1 op3 op2 // op3 op4 order is not enforced
> test op3 op1 op2
But the following are illegal:
> test op2 op1 // op1 op2 order is enforced
> test op1 op3 op4 // op1 and op2 are mandatory
For the following command, use “cerr” (instead of “cout”) to print out the error
2.1 Command “DBAPpend”
Usage: DBAPpend <(string key)><(int value)>
Description: Append an JSON element (i.e. key-value pair) to the end of the DB.
The options <(string key)><(int value)> must present. If any of the
arguments is missing, print out an error. “key” is composed of
English letters (i.e. a-z, A-Z), digits (i.e. 0-9), and underline symbol
(i.e. ‘_’). The first character of the “key” must be an English letter or
underline symbol. Use “isValidVarName(const string&)” in
“util/myString.cpp” to check the validity of the “key”. If any error
occurs, or if there already exists a JSON element with the same key
(no matter the specified value is the same or not), print out an error.
“value” must be a valid integer. Otherwise, print out an error. No
message is printed on the success of insertion. Note that the added
element affects the JSON object in your program only. It will not
change (i.e. write back to) the read-in file.
If the JSON file hasn’t been read in, print out an error message
“Error: DB is not created yet!!”.
mydb> DBAPpend Mary 30
mydb> DBAPpend KK 4 // Assume { “KK” : 4 } already exists
Error: Element with key “KK” already exists!!
mydb> dbAPpend
Error: Missing option!!
mydb> dbAPpend ric2k1
Error: Missing option!!
mydb> DBAPpend Mary ric2k1
// Any of the error message is OK
Error: Missing option after “Mary”!!
Error: Illegal option!! (ric2k1)
2.2 Command “DBAVerage”
Usage: DBAVerage
Description: Print out the average of the values in the DB. Use “fixed” and
“setprecision(2)” for cout to control the output precision. If the DB is
empty, report NAN (a float const number, #include ) as an
mydb> DBAVe
The average of the DB is 13.38.
mydb> DBAVe
Error: The average of the DB is nan.
2.3 Command “DBCount”
Usage: DBCount
Description: Print out the number of JSON element(s) in the DB. Be noted on the
singular and plural forms of “element(s)”.
mydb> DBCount
There are 57 JSON elements in DB.
mydb> DBCount
There is 1 JSON element in DB.
mydb> DBCount
There is no JSON element in DB.
2.4 Command “DBMAx”
Usage: DBMAx
Description: Print out the maximum JSON element (i.e. with the maximum value)
in the DB. If there are multiple elements with the same maximum
value, print out either one (preferably, the first one encountered). If
the DB is empty, report NAN (a float const number, #include
) as an error.
mydb> DBMAx
The max JSON element is { “Mary” : 100 }.
mydb> DBMAx
Error: The max JSON element is nan.
2.5 Command “DBMIn”
Usage: DBMIn
Description: Print out the minimum JSON element (i.e. with the minimum value)
in the DB. If there are multiple elements with the same minimum
value, print out either one (preferably, the first one encountered). If
the DB is empty, report NAN (a float const number, #include
) as an error.
mydb> DBMIn
The min JSON element is { “John” : -87 }.
mydb> DBMIn
Error: The min JSON element is nan.
2.6 Command “DBPrint”
Usage: DBPrint [(string key)]
Description: Print out the JSON DB. If the option “key” is NOT specified, print
out the entire JSON object. On the other hand, if the option “key” is
specified, print out the JSON element with the the “key” (i.e.
performing case-sensitive comparison). If not found, print out an
error. The printing format is as shown in the example.
If the JSON file hasn’t been read in, print out an error message
“Error: DB is not created yet!!”.
mydb> DBPrint
“Ric” : 100,
“John” : 50
Total JSON elements: 2
mydb> DBPrint Ric
{ “Ric” : 100 }
mydb> DBPrint ric
Error: No JSON element with key “ric” is found.
2.7 Command “DBRead”
Usage: DBRead <(string jsonFile)> [-Replace]
Description: Read the data from “jsonFile” to the database (DB). If file “jsonFile”
doesn’t exist, print out an error message. If the DB already exists and
the option “-Replace” is not specified, issue an error. If the option “-
Replace” is given, replace the DB content with the data in the
mydb> DBRead test1.json // assume test1.json doesn’t exist
Error: “test1.json” does not exist!!
mydb> DBRead test2.json // assume DB already exists
Error: DB exists. Use “-Replace” option for replacement.
mydb> DBRead test3.json -rep
DB is replaced…
“test3.json” was read in successfully.
2.8 Command “DBSOrt”
Usage: DBSOrt <-Key | -Value>
Description: Sort the JSON elements with key (-Key) or value (-Value) in
ascending order. No output message is needed for this command,
even if the JSON object is empty.
mydb> DBSOrt
Error: Missing option!!
mydb> DBSOrt -Key
mydb> DBSOrt -Value
2.9 Command “DBSUm”
Usage: DBSUm
Description: Print out the summation of the values of the JSON elements in the
DB. If the DB is empty, report NAN (a float const number, #include
) as an error.
mydb> DBSUm
The sum of the DB is 2880.
mydb> DBSUm
Error: The sum of the DB is nan.
2.10 Command “DOfile”
Usage: DOfile <(string filename)>
Description: Execute the commands in the dofile. After the execution, it should
go back to the command prompt.
mydb> dofile dofile1
2.11 Command “HELp”
Usage: HELp [(string cmd)]
Description: Print out help message. If command is specified, print out its usage.
Otherwise, print out the list of all commands with simple
mydb> help
mydb> help dofile
mydb> help do
2.12 Command “HIStory”
Usage: HIStory [(int nPrint)]
Description: Print command history. The argument specifies the upper bound of
how many of the last command history entries it will print. If not
specified, all the histories will be printed.
mydb> history 8
2.13 Command “Quit”
Usage: Quit [-Force]
Description: Quit the execution. Prompt a confirmation if the argument “-Force”
is not present.
mydb> quit
mydb> q –f
3. Implementation
3.1 File/Directory Structure
After decompressing the .tgz file, you should see the following files and
hw3> ls -aF
Homework_3.docx Homework_3.pdf Makefile MustExist.txt
MustRemove.txt bin/ dofiles/ include/ lib/ mydb@ ref/
src/ testdb@ tests/
“bin/” and “lib/” are the directories to store the binary (executable) and library
files, respectively. “Makefile” is the top-level makefile. You only need to type
“make” in this root directory and it will go to different source code directories to
invoke other makefiles, check the file dependency, compile the source codes, create
libraries and final executable, and return. The generated executable will be stored in
“bin/” and a symbolic link “mydb” will be created in this directory for the easy access
of the executable. “testdb” is another executable/symbolic link for testing your DB
operations. Please see Section 4 for details.
“dofiles/” contains some dofiles for you to test, and “ref/” includes the reference
executables for linux and mac platforms. Please play with them to understand the spec
of the commands in this homework. “tests/” directory contains some .json files for
you to test.
The directory “include/” contains the symbolic links of the header files (.h) to be
shared within different source code packages. The “src/” contains the source codes of
different packages, each defined in a sub-directory. In this homework, the packages
under “src/” include:
hw3> ls src
cmd/ db/ main/ Makefile.lib test/ util/
The “main/” directory, as its name suggests, contains the main() function of the
entire program. “cmd/” implements the utilities of the command interface. It also
defines some common commands such as “help”, “quit”, “history”, etc. The “db/”
directory is for the simple command-line database manager. The common utilities,
such as customized string functions, memory management, container classes, etc,
should be placed under the “util/” directory. You should try to take advantages of
these common utility functions.
The “test/” directory is to test your “db/” implementation before completing the
command interface. Please see Section 4 “What you should do?” for further guidance.
3.2 Class description
1. Classes about command registration: class CmdParser, class
CmdExec and its derived classes
In this program, commands in different packages (i.e. different source code
directories) are “registered” through the CmdParser command manager.
There is one global variable cmdMgr and commands are added through its
regCmd() member function. For example, in file “cmdCommon.cpp”:
if (!(cmdMgr->regCmd(“Quit”, 1, new QuitCmd) &&
cmdMgr->regCmd(“HIStory”,3,new HistoryCmd)&&
cmdMgr->regCmd(“HELp”, 3, new HelpCmd) &&
cmdMgr->regCmd(“DOfile”, 2, new DofileCmd)
)) {
cerr << "Registering \"init\" commands fails..." << " exiting" << endl; return false; } return true; } Four commands (quit, history, help, dofile) are registered to the cmdMgr. The first parameter of the CmdParser::regCmd() function specifies the name of the command. Please note that the leading capital characters (e.g. HIS in HIStory) are mandatory matching. They are made capital for conventional reason. The second parameter specifies the number of the mandatory matching characters. The last parameter is a functional object that inherits the class CmdExec. 10 The class CmdExec is the common command registration and execution interface. To create a new command, you need to declare a derived class such as class QuitCmd which defines at least the following three member functions: (1) exec(): parse the command option(s) and execute the command, (2) usage(): print out the command usage, and (3) help(): print out the command definition for the HELp command. For more details, please refer to functions CmdParser::regCmd(), CmdParser::execOneCmd() in file “cmdParser.cpp”, and exec/usage/help() members functions of each derived class such as in file “cmdCommon.{h,cpp}”. For the sake of convenience, we define a MACRO CmdClass(T) in the file “cmdParser.h” so that we can easily declare an inherited class of CmdExec as: CmdClass(HelpCmd); Please refer to the file “cmdCommon.cpp” for more examples. 2. Classes about keyboard mapping: class CmdParser and enum ParseChar The class CmdParser defines the functions to process inputs from the standard (cin) and file inputs, and the enum ParseChar is to define the keyboard mapping. Please note that the grading of this homework will not include special keys such as “delete”, “backspace” and arrow keys, etc. So you can actually ignore them. (i.e. Don’t worry about the keyboard mapping) We will focus on testing the command registration and database’s functionalities. In fact, in “src/” we actually define the flag “TA_KB_SETTING” in the macro CFLAGS and thus we will use our keyboard mapping by default. However, if you want to customize your keyboard mapping, please change the “#ifndef” part of the “#ifndef TA_KB_SETTING” in files “cmdParser.h”, “cmdCharDef.cpp” and undefine “TA_KB_SETTING” in the macro CFLAGS of “src/”. 3. Classes about database manager: The classes and member functions for JSON element and object are defined in files “dbJson.{h,cpp}”. The class DBJson defines all the interfaces to manipulate the JSON object, and its data member “vector _obj” stores the JSON elements.
The class DBJsonElem represents the JSON element, and the struct
DBSortKey and DBSortValue are used as StrictWeakOrdering
functional objects for the STL sort() algorithm.
3.3 How is a command string stored in _cmdMap?
When a command is registered in the CmdParser::cmdReg() function, the
command string is partitioned into two parts: the former mandatory part (e.g. “HEL”
in “HELp” command) will be converted to all-capital and used as the key to store the
command in CmdParser::_cmdMap. Note that the characters are made all capital in
order to facilitate the case-insensitive comparison. The second template argument of
“map CmdParser::_cmdMap” is an inherited
pointer object of class CmdExec. For example, for the command “HELp”, a pointer
object of the inherited class HelpCmd will be created and stored.
The latter optional part of the command string (e.g. “p” in “HELp” command)
will be stored as a private data member “string _optCmd” of the corresponding
class object. It will be checked when parsing the command line input.
3.4 Makefile
There are 5 types of makefiles:
1. Top-level Makefile: for the entire program creation
2. “make.$pkgName” in each of the source code directories: calling
“” and “Makefile.lib” to construct library for each source code
package. In this file, the macro PKGFLAG is to define the compilation flags
specific to this package, EXTHDRS defines the header files that should be
exposed to other (external) packages (so they will be symbolically linked to
the “include” directory), and EXTRAOBJS defines the extra object files that
are not compiled from the .cpp files in this directory.
3. common core for the makefiles in different source code
directories — (i) define the compilation rules, (ii) create file dependencies,
(iii) create symbolic links for the external header files from the source code
directory to the “include” directory.
4. Makefile.lib: makefile to create libraries for each package.
5. “make.main” in the “main” source code directory: to perform linking and
create the final executable.
Before making the program, you are suggested to type “make linux18”, “make
linux16” or “make mac” to configure the provided object file “cmdRead.o” for your
environment. Type “make” for top-level Makefile to create the executable. Use “make
clean” to remove all the objective files, libraries, etc.
3.5 Useful utility functions
Please pay attention that there are many prewritten utility functions that you can
take advantage of for your TODOs. For example, in class CmdExec,
lexNoOption(), lexSingleOption() and lexOptions() can parse the command option
into tokens. In file util/myString.cpp, the function myStrNCmp(const string& s1, const
string& s2, unsigned n) performs case insensitive comparison between s1 and s2 for
the first n characters, and check the compatibility for the rest. The function
myStr2Int(const string& str, int& num) can convert the string “str” to integer “num”,
and the function isValidVarName(const string& str) can check if the parameter “str”
is a valid key for a JSON element.
3.6 Advanced Feature: “Tab” support
When the “tab” key is pressed, all the partially matched commands will be listed.
Depending on the cursor position, there can be several possible responses:
1. If nothing but space characters is before the cursor, pressing “tab” key will
list all the commands.
// Before pressing “tab”
// After pressing “tab”
Note that each command above is printed by:
cout << setw(12) << left << cmd; // cmd is a string And a new line is printed for every 5 commands. After printing, you should re-print the prompt and place the cursor back to its original location (including space characters). 2. If only partial command is matched, pressing “tab” should list all the possible matched commands. (multiple matches) [Example] // Before pressing “tab” mydb> h
// After pressing “tab”
HELp HIStory
mydb> h
3. But if there is only one possible match, pressing tab should complete the
command. A space character will also be inserted after the command to
separate it from the trailing substring. The newly inserted characters should
match the strings stored in CmdParser::_cmdMap and in “string
_optCmd” of the corresponding inherited class object.
// Before pressing “tab”
mydb> hello world
// After pressing “tab”
mydb> heLp llo world
4. If no command can be matched, pressing “tab” will make a beep sound and
the cursor will stay in the same location.
// Before pressing “tab”
mydb> hello world
// After pressing “tab”
mydb> hello world
5. If the string before the cursor has already matched a command, and if there
is at least one space characters before the cursor, pressing “tab” for the first
time will print out its command usage.
// Before pressing “tab”
mydb> hel lo world
// After pressing “tab”
Usage: HELp [(string cmd)]
mydb> hel lo world
After printing, the cursor should remain in the original location.
6. (Continued from 5) If the string before the cursor has already matched a
command, and if there is at least one space characters before the cursor,
pressing “tab” for the second time and onwards will list the file names in the
current directory (Please refer to the function “listDir()” in “util/util.cpp”).
Several possible cases as follow:
(6.1) If the character before the cursor is a space ‘ ‘, there are several
possibilities as follows:
[Example] (applied to 6.1.1 ~ 6.1.3)
// Before pressing “tab”
mydb> hel world
(6.1.1) in this directory there are multiple files and they do not have a
common prefix,
// After pressing “tab” — print out ALL the file names under current
Homework_3.docx Homework_3.pdf Makefile MustExist.txt MustRemove.txt
bin dofiles include lib mydb
ref src testdb tests
mydb> hel world
Note that each filename above is printed by:
cout << setw(16) << left << fileN; // fileN is a string 14 And a new line is printed for every 5 commands. (6.1.2) in this directory there are multiple files and all of them have a common prefix, // After pressing “tab” --- auto insert the common prefix and make a beep sound ==> DO NOT print the matched files and do not re-print the
command line
// (e.g.) Try this in “ref” directory
mydb> hel mydb-world
(6.1.3) only one file in the current directory
// After pressing “tab” — print out the single file name followed by a ‘ ‘
// (e.g.) Try this in “bin” directory
mydb> hel mydb world
// Note: if the “tab” is pressed again, make a beep sound and do not print the
single file name again.
(6.2) If the character before the cursor is NOT a space ‘ ‘, treat the substring
before the cursor as a “prefix”. If there are multiple files under current
directory that match the prefix, print out ALL the file names that match the
// Before pressing “tab”
mydb> hel McDonald
// After pressing “tab”
Makefile MustExist.txt MustRemove.txt
mydb> hel McDonald
(6.3) However, if in (6.2) the multiple matched file names have a common
prefix, automatically insert the common prefix to the command line and
make a beep sound. DO NOT print out the matched files and do not re-print
the command line.
// Before pressing “tab”
mydb> hel MucDonald
// After pressing “tab”
mydb> hel MustcDonald
// Note: if the “tab” is pressed again, it will match the case (6.2) and print
out MustExist.txt and MustRemove.txt
(6.4) In (6.2), if there is only ONE matched file, insert the remaining of the
matched file name followed by a space ‘ ‘.
// Before pressing “tab”
mydb> hel MustEcDonald
// After pressing “tab”
mydb> hel MustExist.txt cDonald
// Note: if the “tab” is pressed again, make a beep sound and do not print the
single file name again.
(6.5) In (6.2), if there is NO matched file for the prefix, make a beep sound
and leave the cursor in the original position.
// Before pressing “tab”
mydb> hel Yellow
// After pressing “tab”
mydb> hel Yellow
7. If the first word is not a match of a single command, and the cursor is not on
the first word, pressing “tab” should make a beep sound and the cursor will
stay in the same location.
// Before pressing “tab”
mydb> he llo world
// After pressing “tab”
mydb> he llo world
Please note that this is an advanced feature. Do this only if you have completed
all the other TODO’s.
3.7 Adding new source code directory (not required in this
1. Under “src” directory, create a new subdirectory. Name the directory
properly as the package name.
2. In the top-level makefile, add the package name (usually equal to the
directory name) to the macro “LIBPKGS”.
3. In the new package directory, copy the “make.$packageName” from other
source code directory and rename its suffix with the package name. Remove
the assignment on the “EXTHDRS” variable if any. Add in header file name
to the “EXTHDRS” later if you intend to share that header file with other
4. What should you do?
You are encouraged to follow the steps below for this homework assignment:
1. Read the specification carefully and make sure you understand the
2. Think first how you are going to write the program, supposed you don’t have
the reference code…
3. Study the provided source code. Please be advised that the number of lines of
the reference code is 2118. If you have never handled a software program in
such a scale before, please read it “smartly”. You may want to first figure out
the layout of files and directories, major data structure (i.e. classes), and how
the functions are called starting from “main()”. Please don’t dig into detailed
implementation in the beginning. Try to “guess” the meaning of the functions
and variables, and have a “global” view of the program first. You can also
use “ctags” to trace the codes. For more information about “ctags”, please
refer to the third tip in Section 5.
4. What you should do in this homework assignment are commented with
“TODO”’s. You should be able to complete this assignment by just finishing
these todo’s. Roughly speaking, they contain 6 parts:
(i) Complete the DJson and DBJsonElem classes (in DBJson.h and
DBJson.cpp). Their functionalities are quite similar to Homework #1,
but with some differences. Please read the descriptions carefully in
Sections 1 and 2.
(ii) You can test your DBJson and DBJsonElem implementation with the
test program in the “test/” directory. Please refer to the main() function
in test.cpp to add more testing codes. Simply type “make test” in the
homework root directory to generate the test program “testdb”. Although
testdb will not be included in the homework grading, you are
encouraged to test more on your DBJson implementation before
moving on to command interface.
(iii) Finish the command interface in “cmdParser.cpp”. You need to know
how to use STL “string”, “map” and “vector”.
(iv) Implement the commands for “db” package (in dbCmd.cpp). You need
to analyze the command line to see if there is any syntax error. Please
note that there are several useful “string/char*” functions in files
“util/myString.cpp” and “cmd/cmdParser.cpp”. Use them whenever
applicable. In addition, you need to call the appropriate DBJson
member functions for the DB manipulations.
(v) Enhance the command “DOFile”. Please refer to the “TODO” in the
source code “cmdCommon.cpp” for the supported features. You may
need to add or modify member functions or data members of class
CmdParser. However, please place the newly added data members to
the end of class CmdParser as the object file cmdReader.o is
precompiled. If you insert data member in front of or in between existing
data members, you may corrupt the relative memory addresses of the
precompiled objects in cmdReader.o. For more information about
how/what to add for command “DOFile”, please refer to the fourth and
fifth tips in Section 5.
(vi) Implement the “tab” function (i.e. CmdParser::listCmd() in
5. Complete your coding and compile it by “make”. Test your program
frequently and thoroughly. Please note that we provide the complete code for
the command line parser so that you don’t need to worry about the
correctness and completeness of your Homework #2. However, we only
provide the object file (i.e. cmdReader.o) so that it can be used for future
homework assignment. Please note that the object file is platform dependent.
Different platforms may require different compilations of object files. We
provide three versions of cmdReader.o: (1) cmdReader.o.linux18 for
Ubuntu 18 LTS linux machine, (2) cmdReader.o.linux16 for Ubuntu 16
LTS linux machine, and (3) cmdReader.o.mac for MAC. The file
“cmdReader.o” is actually a symbolic link to one of them. The default is
“cmdReader.o.linux18”. Please type “make linux18”, “make linux16” or
“make mac” to switch between different platforms.
6. Reference programs mydb-linux18 / mydb-linux16 / mydb-mac (for the
simple command-line JSON object manipulations) are available under the
“ref/” directory. Please use them to compare your result. Please also watch
out the announcements in the Ceiba website and FB group.
7. Rename the homework root directory to yourID_hw3 and type “make
clean” to remove the executables and object files. Compress the directory by
the command (on Linux or Mac Terminal):
tar zcvf yourID_hw3.tgz yourID_hw3
Submit the .tgz file to Ceiba before deadline.
5. Some tips you should know
1. The provided reference code can be compiled even though the TODOs are not
done. However, the produced executable cannot run (i.e. will crash). Please
check the TODO’s and implement some of them first.
2. Sometimes you may encounter compilation error message like:
make[1]: *** No rule to make target `../../include/util.h’, needed by `cmdCommon.o’. Stop.
This is mainly because the hidden file “.extheader.mak” in some directory is
accidentally removed. You can try to “make clean” and “make” again and
usually it will resolve the problem.
3. Type “make ctags” to create ctages for all the source codes. Be sure to add in
the following line in your “$HOME/.vimrc” (if you use “vim” and don’t have
this file, create one):
set tags=./tags,../tags
Then when you use “vim” to edit the source code, you can jump to the
function/class definition of the identifier your cursor is currently on by
pressing “ctrl-]”. To come back, simply press “ctrl-t”.
4. The function closeDofile() is a TODO. However, how it is called is not
included in the reference code. Here is the partial code of the function
readCmd() in cmdReader.cpp . You can see how closeDofile() is called.
CmdParser::readCmd(istream& istr)
bool newCmd = false;
while (!newCmd) {
ParseChar pch = getChar(istr);
if (pch == INPUT_END_KEY) {
if (_dofile != 0)
switch(ch) {
… // Refer to the codes in homework #2
return newCmd;
5. The handling of “ifstream* _dofile” for the “openDofile()” and
“closeDofile()” may be trickier than you think. For example, if you
need to open a dofile (i.e. the DOfile command) in a dofile, you need to
store the original dofile and when the new dofile is finished, retrieve it and
continue the execution from where you left. However, please note that you
CANNOT “copy” fstream object. That’s why we declare _dofile as a
6. In “cmdReader.o”, there is a function “CmdParser::reprintCmd()”
called by “CmdParser::listCommand()”, which is for the “tab” feature.
Although you don’t have the cmdReader.cpp source code, you are free to call
the function reprintCmd():
// Reprint the current command to a newline
// cursor should be restored to the original
cout << endl; char *tmp = _readBufPtr; _readBufPtr = _readBufEnd; printPrompt(); cout << _readBuf; moveBufPtr(tmp); } 7. When you use output directing operator “>” to store the output of your
program to a file, please note that only “standard output” is directed. The error
message (i.e. “standard error” cerr) is not included. For “csh/tcsh”, you need
to use “>&” instead. For bash, you can try “&>” or something like:
“./mydb-ref -File dofile.ref > out.mine 2>&1” or
“./mydb-ref -File dofile.ref 2>&1 | tee out.mine”
6. Grading
We will test your submitted program with various combinations/sequences of
commands to determine your grade. The results (i.e. outputs) will be compared with
our reference program. Minor difference due to printing alignment, spacing, etc can
be tolerated. However, to assist TAs for easier grading work, please try to match your
output with ours.