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fercgomes / ellerre

An LR grammar automata generator (yet to be completed)

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EllErre - An LR automata generator

EllErre is designed to be an LR automata generator, with the following algorithms:

  • [X] First Set
  • [X] Follow Set
  • [X] LR(0) automata
  • [ ] SLR(1) automata
  • [X] LR(1) automata
  • [X] LALR(1) automata
  • [X] GraphViz automata representation
  • [ ] Step by Step GraphViz automata representation
  • [ ] Mark inital and end states in the automata

It is current in development.

For now, it calculates the First/Follow sets, the LR(0), LR(1) and LALR(1) automatas for a given grammar.

Installation & Compilation

sudo apt-get install git cmake build-essential flex bison;
git clone git://github.com/schnorr/ellerre.git ; mkdir -p ellerre/b ; cd ellerre/b ; cmake .. ; make
  • If you want to visualize the automatas with graphviz
sudo apt-get install graphviz

Compilation only

mkdir -p build ; cd build ; cmake .. ; make
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found FLEX: /usr/bin/flex (found version "2.6.4") 
-- Found BISON: /usr/bin/bison (found version "3.0.4") 
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/ellerre/build
[ 11%] [BISON][parser] Building parser with bison 3.0.4
[ 22%] [FLEX][scanner] Building scanner with flex 2.6.4
Scanning dependencies of target ellerre
[ 33%] Building CXX object CMakeFiles/ellerre.dir/src/main.cc.o
[ 44%] Building CXX object CMakeFiles/ellerre.dir/src/symbol.cc.o
[ 55%] Building CXX object CMakeFiles/ellerre.dir/src/rule.cc.o
[ 66%] Building CXX object CMakeFiles/ellerre.dir/src/grammar.cc.o
[ 66%] [BISON][parser] Building parser with bison 3.0.4
[ 77%] Building CXX object CMakeFiles/ellerre.dir/scanner.cc.o
[ 88%] Building CXX object CMakeFiles/ellerre.dir/parser.cc.o
[100%] Linking CXX executable ellerre
[100%] Built target ellerre

Execution

First and Follow

cd build
./firstfollow < ../examples/ex1.ee
Grammar with 3 rules and 4 symbols (2 non-terminals):
S => A A 
A => a A 
A => b 

First sets:
S -- b a 
A -- b a 

Follow sets:
S -- $ 
A -- $ b a

LR(0) automata

cd build
./lr0 < ../examples/ex1.ee
Grammar with 4 rules and 4 symbols (2 non-terminals):
S' ⇒ S 
S ⇒ A A 
A ⇒ a A 
A ⇒ b 

LR0 item set:
S' ⇒ • S 
S' ⇒ S • 
S ⇒ • A A 
S ⇒ A • A 
S ⇒ A A • 
A ⇒ • a A 
A ⇒ a • A 
A ⇒ a A • 
A ⇒ • b 
A ⇒ b • 

LR0 automata:
State 0:
S' ⇒ • S 
---------------
S ⇒ • A A 
A ⇒ • a A 
A ⇒ • b 
Transitions: 
S ---> 1
A ---> 2
b ---> 3
a ---> 4

State 1:
S' ⇒ S • 
---------------

State 2:
S ⇒ A • A 
---------------
A ⇒ • a A 
A ⇒ • b 
Transitions: 
A ---> 5
b ---> 3
a ---> 4

State 3:
A ⇒ b • 
---------------

State 4:
A ⇒ a • A 
---------------
A ⇒ • a A 
A ⇒ • b 
Transitions: 
A ---> 6
b ---> 3
a ---> 4

State 5:
S ⇒ A A • 
---------------

State 6:
A ⇒ a A • 
---------------

LR(1) automata

cd build
./lr1  < ../examples/ex1.ee
Grammar with 4 rules and 4 symbols (2 non-terminals):
S' => S 
S => A A 
A => a A 
A => b 

First set: 
S -- b a 
A -- b a 
S' -- b a 

Follow set: 
S -- $ 
A -- $ b a 
S' -- $ 

LR1 item set:
S' => • S , $
S' => S • , $
S => • A A , $
S => A • A , $
S => A A • , $
A => • a A , $
A => • a A , b
A => • a A , a
A => a • A , $
A => a • A , b
A => a • A , a
A => a A • , $
A => a A • , b
A => a A • , a
A => • b , $
A => • b , b
A => • b , a
A => b • , $
A => b • , b
A => b • , a

LR1 automata:
State 0:
S' => • S , $
---------------
S => • A A , $
A => • a A , b
A => • a A , a
A => • b , b
A => • b , a
Transitions: 
S ---> 1
A ---> 2
b ---> 3
a ---> 4

State 1:
S' => S • , $
---------------

State 2:
S => A • A , $
---------------
A => • a A , $
A => • b , $
Transitions: 
A ---> 5
b ---> 6
a ---> 7

State 3:
A => b • , b
A => b • , a
---------------

State 4:
A => a • A , b
A => a • A , a
---------------
A => • a A , b
A => • a A , a
A => • b , b
A => • b , a
Transitions: 
A ---> 8
b ---> 3
a ---> 4

State 5:
S => A A • , $
---------------

State 6:
A => b • , $
---------------

State 7:
A => a • A , $
---------------
A => • a A , $
A => • b , $
Transitions: 
A ---> 9
b ---> 6
a ---> 7

State 8:
A => a A • , b
A => a A • , a
---------------

State 9:
A => a A • , $
---------------

LALR(1) automata

cd build
./lalr1  < ../examples/ex1.ee
Grammar with 4 rules and 4 symbols (2 non-terminals):
S' => S 
S => A A 
A => a A 
A => b 

First set: 
S -- b a 
A -- b a 
S' -- b a 

Follow set: 
S -- $ 
A -- $ b a 
S' -- $ 

LALR1 item set:
S' => • S , $
S' => S • , $
S => • A A , $
S => A • A , $
S => A A • , $
A => • a A , $
A => • a A , b
A => • a A , a
A => a • A , $
A => a • A , b
A => a • A , a
A => a A • , $
A => a A • , b
A => a A • , a
A => • b , $
A => • b , b
A => • b , a
A => b • , $
A => b • , b
A => b • , a

LALR1 automata:
State 0:
S' => • S , $
---------------
S => • A A , $
A => • a A , b
A => • a A , a
A => • b , b
A => • b , a
Transitions: 
S ---> 1
A ---> 2
b ---> 3
a ---> 4

State 1:
S' => S • , $
---------------

State 2:
S => A • A , $
---------------
A => • a A , $
A => • b , $
Transitions: 
A ---> 5
b ---> 3
a ---> 4

State 3:
A => b • , $
A => b • , b
A => b • , a
---------------

State 4:
A => a • A , $
A => a • A , b
A => a • A , a
---------------
A => • a A , $
A => • a A , b
A => • a A , a
A => • b , $
A => • b , b
A => • b , a
Transitions: 
A ---> 6
b ---> 3
a ---> 4

State 5:
S => A A • , $
---------------

State 6:
A => a A • , $
A => a A • , b
A => a A • , a
---------------

Generating the visual representation of the automata

Each parser execution from EllErre generate a .dot file after its execution. The dot files are named after its parsing algorithm (LR0.dot, LR1.dot, and LALR1.dot).

This files can be used by tools like graphviz to generate a visual representation of the given LR automata.

Example

Running the example

The following execution generates the “LR0.dot” file, which describes the automata in the using the .dot syntax.

cd build
./lr0 < ../examples/ex1.ee >> /dev/null
cat LR0.dot
digraph g { graph [fontsize=30 labelloc="t" label="" splines=true overlap=false rankdir = "LR"]; ratio = auto;
	"state0" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #0</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">S' ⇒ • S 
</font></td></tr>
		<tr><td align="left" port="r1"><font color="gray25" face="bold">S ⇒ • A A 
</font></td></tr>
		<tr><td align="left" port="r2"><font color="gray25" face="bold">A ⇒ • a A 
</font></td></tr>
		<tr><td align="left" port="r3"><font color="gray25" face="bold">A ⇒ • b 
</font></td></tr>
	</table>>];

	"state1" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #1</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">S' ⇒ S • 
</font></td></tr>
	</table>>];

	"state2" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #2</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">S ⇒ A • A 
</font></td></tr>
		<tr><td align="left" port="r1"><font color="gray25" face="bold">A ⇒ • a A 
</font></td></tr>
		<tr><td align="left" port="r2"><font color="gray25" face="bold">A ⇒ • b 
</font></td></tr>
	</table>>];

	"state3" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #3</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">A ⇒ b • 
</font></td></tr>
	</table>>];

	"state4" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #4</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">A ⇒ a • A 
</font></td></tr>
		<tr><td align="left" port="r1"><font color="gray25" face="bold">A ⇒ • a A 
</font></td></tr>
		<tr><td align="left" port="r2"><font color="gray25" face="bold">A ⇒ • b 
</font></td></tr>
	</table>>];

	"state5" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #5</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">S ⇒ A A • 
</font></td></tr>
	</table>>];

	"state6" [ style = "filled" penwidth = 1 fillcolor = "white" fontname = "Courier New" shape = "Mrecord" label = <<table border="0" cellborder="0" cellpadding="3" bgcolor="white">
		<tr><td bgcolor="black" align="center" colspan="2"><font color="white">State #6</font></td></tr>
		<tr><td align="left" port="r0"><font face="bold">A ⇒ a A • 
</font></td></tr>
	</table>>];

state0 -> state1[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "S" ];
state0 -> state2[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "A" ];
state0 -> state3[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "b" ];
state0 -> state4[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "a" ];
state2 -> state5[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "A" ];
state2 -> state3[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "b" ];
state2 -> state4[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "a" ];
state4 -> state6[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "A" ];
state4 -> state3[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "b" ];
state4 -> state4[ penwidth = 3 fontsize = 22 fontcolor = "black" label = "a" ];
}

Generating the image

cd build
dot -Tpng LR0.dot -o LR0_output.png

./examples/LR0_output.png

About

An LR grammar automata generator (yet to be completed)

License:GNU General Public License v3.0

Languages

Language:C++ 93.4%Language:Yacc 3.2%Language:CMake 2.0%Language:Lex 1.5%