The GG Programming Language

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The GG Programming Language

• We give it to you.

2
The Authors

• Kierstan Bell
• Documentation and Front-end
• Elizabeth Mutter
• Front-end
• Jake Porway
• Testing and Front-end
• Jonah Tower
• Back-end

3
Language Overview

• Jonah

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Why GG?
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it makes things easy!

• Sockets
• I/O
• Threads

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Sockets a Simple Client

• include ltstdio.hgt
• include ltstdlib.hgt
• include ltstring.hgt
• include ltunistd.hgt
• include ltsignal.hgt
• include lterrno.hgt
• include ltsys/types.hgt
• include ltsys/socket.hgt
• include ltsys/wait.hgt
• include ltnetinet/in.hgt
• / sklar need to define socklen_t for cunix not
  needed for linux /
• / typedef int socklen_t /
• define TERM '\n'

• /------------------------------------------------
  --------------------
• client_sock()
• creates a socket and then attempts to make a
  connection to that
• socket
• ------------------------------------------------
  ------------------/
• int client_sock ( int port )
• int ss, optval 1
• struct sockaddr_in sin
• / (1) create an endpoint for communication
  /
• if (( ss socket( PF_INET, SOCK_STREAM, 0 ))
  -1)
• sysabort( "client/socket" )
• / (1a) set socket options /
• if ( setsockopt( ss,

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This is Really Simple

• / (2) make a connection to the server socket /
• if ( connect( ss,(struct sockaddr
  )sin,(socklen_t)sizeof(sin) ) -1 )
• printf("foobar\n")
• sysabort( "client/connect" )
• / return the socket descriptor /
• return( ss )
• / end of client_sock() /
• /------------------------------------------------
  --------------------
• echo_client()
• ------------------------------------------------
  ------------------/
• void echo_client ( int port )
• int sock, olen, nwritten, nread, more
• unsigned char i

• p0 TERM
• p1 '\0'
• else
• printf( "client writing message s\n",p
  )
• i strlen( p )
• if (( nwritten write( sock, i, sizeof( i ) ))
  -1 )
• sysabort( "client/write" )
• if (( nwritten write( sock, p, strlen(p) ))
  -1 )
• sysabort( "client/write" )
• if ( more )
• if (( nread read( sock, i, sizeof( i )))
  lt 0 )
• sysabort( "client/read" )
• fprintf( stdout,"client id\n",i )
• fflush( stdout )

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Still going

• / end of echo_client() /
• /------------------------------------------------
  --------------------
• main()
• ------------------------------------------------
  ------------------/
• int main( int argc, char argv )
• int port
• if ( argc lt 2 )
• printf( "usage client.x ltportgt\n" )
• exit( 1 )
• sscanf( argv1,"d",port )
• echo_client( port )
• return( 0 )
• / end of main() /

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And now in GG

• void main(string arg1, string arg2)
• sockconnect(arg1, stoi(arg2))
• while(1)
• send(getline())
• print(recv())

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File I/O (in Java)

• File f new File(foobar.txt)

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File I/O (in Java)

• File f new File(foobar.txt)
• FileReader fr new FileReader(f)

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File I/O (in Java)

• File f new File(foobar.txt)
• FileReader fr new FileReader(f)
• BufferedReader in new BufferedReader(fr)

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File I/O (in Java)

• File f new File(foobar.txt)
• FileReader fr new FileReader(f)
• BufferedReader in new BufferedReader(fr)
• String line in.readLine()

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but wait!

• try
• File f new File(foobar.txt)
• FileReader fr new FileReader(f)
• BufferedReader in new BufferedReader(fr)
• String line in.readLine()
• Catch(IOException e)
• System.err.println(Oh no!)

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Look at our Cool Version

• file f foobar.txt
• string line fgetline(f)

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And, GG lets youthread things

• WOW!

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Syntax and Semantics

• Kierstan

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This is Like C, Baby!

• Functional language
• NOT Object Oriented
• C-like syntax

int x int foo(int i) int y y i
1 return y
void main() int z x 10 z foo(x)
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Data Types

• boolean
• boolean b true
• boolean b false
• char
• char a a
• file
• file myFile myFile.txt
• int
• int i 0
• string
• string hi hi

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Control Flow

• while statement
• if

while(ltbooleangt) statements
if(ltbooleangt) statements
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Built-in Functions

• string fgetline(file f)
• void fprint(file f, string option, string line)
• int getint()
• string getline()
• string getlocalhost()
• int getTime()
• void print(string line)
• string recv()
• string recv(int port)
• void send(file file)
• void send(file file, int port)
• void send(string line)
• void send(string line, int port)
• void socketclose()
• void socketclose(int port)
• int socketcreate()
• int socketcreate(int port)
• int socketconnect(int port)
• int socketconnect(string host, int port)

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Threaded Functions

• threaded void funcA()
• print(a)
• threaded void funcB()
• print(b)

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The Compiler

• Elizabeth

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(No Transcript)
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Lexer/Parser

• Both written in ANTLR
• Lexer
• Parses a GG file into Tokens
• Parser
• Takes the Lexers tokens as input
• Checks for syntax errors
• Creates a tree

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Building the Tree

• For example -
• GG assignment statement
• a myFunc()

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Walking the Tree

• Semantic check AND code generation done in one
  pass
• Uses ANTLRs tree walker
• Walks the dummy nodes
• but java code does most of the work
• Semantic
• Hashtables keep track of
• Global variables
• Local variables
• Function declarations
• Keywords
• Code
• Prints java code to .java files

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Code Generation Java Files

• name-of-file.java
• Runnable java file
• name-of-fileMainMethod.java
• Wrapper class that contains the translated GG
  code
• name-of-functionThreadedFunction.java
• Created for each threaded function

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Testing and Lessons Learned

• Jake

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Standard Regression Testing

• No surprises here
• Small modules tested against base cases using
  script
• Syntactic tests run with Lexer/Parser
• Semantic tests run with Tree Walker
• Generated code checks run by hand

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Syntactic Error Checking

• Checks syntax in Lexer/Parser
• Basic syntactic errors introduced into correct
  reference cases
• Resulting trees are compared
• Base Case
• void main()
• int a 3 ? (FUNC_DECL void
  main (BODY ( a 3)))
• Error
• void main()
• int a 3 ? Expected SEMI
  found CCURLY

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Semantic Error Checking

• Only need to check select semantic errors, since
  most egregious errors are syntactic
• Keep log of test results, check for failure
• void main()
• int a Not a string
• Prints to log file
• test1-typecheck-incorrect.gg
• Result Expected type int but got Not a
  string

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Code Correctness

• Not done with automated checking
• No mortal should have to hand-generate the Java
  base case for a client/server program
• Instead, functionality is checked thoroughly, not
  code

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Lessons Learned!

• Roles are great, but dont be afraid to
  diversify
• Meetings, meetings, and more meetings! Theres
  comfort in consistency
• Clairvoyance Who knew ANTLR would be so hard
• Ctrl-1-0-0 Who put this in Emacs?

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THE END