Turtle

LOGO Interpreter code challange

As an experiment in writing an interpreter I picked up a very old code challange from my works archives.
Initially written with the ancient art of Java swing for the GUI, as per the original challange.
Perhaps will convert to more modern framework. (Flutter?)

Building

The application uses maven to build.
To generate a new build, from the cloned repository root type:

mvn clean package

This will generate the new jar in the target directory under the name: turtle-1.0-SNAPSHOT-jar-with-dependencies.jar.

Usage

java -jar ./target/turtle-1.0-SNAPSHOT-jar-with-dependencies.jar

GUI

The Main screen has three panels:

• Draw Panel
  Displays the graphic output of the commands.
• Command Panel
  The Edit panel to view and enter commands
• Console
  Displays output and error information.

Draw Panel

Draw Panel contains the Turtle, showing the current draw point.
As commands are entered, the Turtle will react and leave a path of lines behind it, forming a graphic.

Command Panel

The command panel is where you enter commands for the turtle.
Type a command and hit enter and that command will be passed to the Turtle. Hitting enter on any line will execute the last line above the cursor.
To execute the entrie window of commands, use the Run all button.
Right clicking on this window gives an option menu to clear the screen.
The command panel may be saved or loaded from file using the file menu.

Console

The console panel is where the output of the commands and any errors are displayed.
It is a mirror of the Standard OUT and Standard ERR streams.
Right clicking on this window gives an option menu to clear the screen.

Toobar

The Menu bar contains some simple navigation buttons to move the turtle and control the Pen.
Clicking the 'Draw' button will enable the pen (pen down command). The command will be entered into the command screen.

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Logo

The Language consists of simple commands which use one or more parameters.
e.g. forward 10
This will move the turtle forward 10 'units'.

Commands may be followed by additional commands using a space to seperate them.
e.g. forward 10 right 90 forward 20
This produces three commands, Forward, right and forward. Any number of commands may be strung together like this.

Basic Turtle commands:

Command	Abbreviations	Argument(s)	Description	Example
forward	fd	Single number of units to move	Moves forward at the current angle of rotation	fd 25
back	bk	Single number of units to move	Moves backwards at the current angle of rotation	bk 25
left	lt	Single number of the angle to rotate	Rotates the turtle by the number of degrees	lt 90
right	rt	Single number of the angle to rotate	Rotates the turtle by the number of degrees	rt 90

The Turtle leaves a path trace to draw a line whenever the "pen" is on.
To ensur ethe pen is on use the pen down commands. The path can be cleared using the clean command.

Additional control commands:

Command	Abbreviations	Argument(s)	Description	Example
pen	pu, pd, draw	Single argument of "yes/no" or up/down or true false	Controls the pen state. When pen is down the path is drawn.	pen down
hideturtle	ht	none	Hides the turtle, leaving just the path on screen	hideturtle
showturtle	st	none	Shows the turtle, showing the path and turtle on screen	showturtle
home	hm	none	Moves the turtle to the center of the screen without leaving a path. Current path is unchanged.	home
clean	cn	none	Clears the current path, leaving turtle in position	clean
cleanscreen	cs	none	Clears the current path, returns turtle to home	cleanscreen

Repeating

Commands may be repeated any number of times using the repeat command.
Repeat has a 'count' number to define the number of times to repeat, followed by a 'code block',
A series of commands enclosed in square brackets.
e.g. repeat 4 [ fd 20 lt 90 ]
This will execute the commands fd 20 lt 90 four times, generating a square.

Patterns

Patterns are predefined commands grouped into a single name.
They are similar to simple 'functions'. Once defined, the pattern name can be used to execute all the grouped commands in the pattern.

A pattern is defined using the pattern command, followed by the pattern name, followed by a 'code block',
A series of commands enclosed inside square brackets.
e.g. pattern square [ fd 10 lt 90 fd 10 lt 90 fd 10 lt 90 fd 10 ]
Defining the pattern has no output, but creates the new square command.
After defining the pattern it may be called by simply giving its name.
e.g. square

Both repeat and pattern may be nested inside each other.
e.g. pattern square [ repeat 4 [ fd 10 lt 90 ]]
This will create a new pattern which generates exxactly the same as the previous square example.

Pattern Arguments

Patterns may define arguments, which must be provided when the pattern is called.
To define an argument use the {} placeholder to mark where that value should appear within the pattern.
e.g. pattern square [ repeat 4 [ fd {} lt 90 ]]
The forward command will use the argument following square to define the forward distance.
square 40 or square 3 draws squares of different sizes.
Arguments are placed in each placehold in the order they appear.

Instruction commands:

Command	Abbreviations	Argument(s)	Description	Example
repeat	rt	Single number of repeat count followed by a 'code block' of commands to repeat.	Repeats the given code block, by the given number of times.	rp 6 [ fd 30 lt 60 ] Draws a hexagon
pattern	pt	A unique name for the pattern followed by a 'code block' of commands	Assigns the given name to the given commands. When the name is used as a command, the given commands are executed.	pt triange [ fd 30 rt 120 fd 30 rt 120 fd 30 ] Creates the triangle command, which draws a triangle.

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Files

The command window can be saved using the file menu or replaced with a file loaded via the open menu.
See the 'examples' directory for sample logo file. Use the 'File/Open' menu to select the logo example,
then click "run all" to execute the sample.

All Commands

Command	Abbreviations	Argument(s)	Description	Example
forward	fd	Single number of units to move	Moves forward at the current angle of rotation	fd 25
back	bk	Single number of units to move	Moves backwards at the current angle of rotation	bk 25
left	lt	Single number of the angle to rotate	Rotates the turtle by the number of degrees	lt 90
right	rt	Single number of the angle to rotate	Rotates the turtle by the number of degrees	rt 90
rotate	-	Single number of the angle to rotate. May be positive or negative number.	Rotates the turtle by the number of degrees	rotate 90
pen	pu, pd, draw	Single argument of "yes/no" or up/down or true false	Controls the pen state. When pen is down the path is drawn.	pen down
colour	color, col, paint	Single argument of named colour or RGB: #RRGGBB hex number	Controls the pen colour.	col red, color cyan col #FFFF00
hideturtle	ht	none	Hides the turtle, leaving just the path on screen	hideturtle
showturtle	st	none	Shows the turtle, showing the path and turtle on screen	showturtle
home	hm	none	Moves the turtle to the center of the screen without leaving a path. Current path is unchanged.	home
clean	cn	none	Clears the current path, leaving turtle in position	clean
cleanscreen	cs	none	Clears the current path, returns turtle to home.	cleanscreen
repeat	rt	Single number of repeat count followed by a 'code block' of commands to repeat.	Repeats the given code block, by the given number of times.	rp 6 [ fd 30 lt 60 ] Draws a hexagon
pattern	pt	A unique name for the pattern followed by a 'code block' of commands	Assigns the given name to the given commands. When the name is used as a command, the given commands are executed.	pt triange [ fd 30 rt 120 fd 30 rt 120 fd 30 ] Creates the triangle command, which draws a triangle.
undo	ud	none	Undo the previous command, removing the last entry in the turtle path.	undo
dump	none	none	Dumps the current state to the console. Shows Turle state & path and current pattern definitions.	dump