net.cscott.sdr.calls
Class ExprList

java.lang.Object
  net.cscott.sdr.calls.ExprList

public class ExprList
extends Object

The ExprList contains ExprFunc definitions and the basic machinery used to evaluate generic Exprs.

Field Summary

static ExprFunc<Fraction>	_ADD_NUM Simple math: addition.
static ExprFunc	_APPLY
static ExprFunc<String>	_COUPLE_NUM_PATTERN The _COUPLE_NUM_PATTERN is mostly for determining when we're "at home".
static ExprFunc<Fraction>	_DIVIDE_NUM Simple math: division.
static ExprFunc<String>	_FACING_PATTERN
static ExprFunc<Fraction>	_FLOOR Simple math: return integer part of a fraction.
static ExprFunc<Fraction>	_FRACTION Simple math: return fractional part of a number.
static ExprFunc	_IF
static ExprFunc<String>	_INOUT_PATTERN Check whether dancers are facing "in" or "out" of the center of the formation.
static ExprFunc<Fraction>	_MOD_NUM Simple math: modulo.
static ExprFunc<Fraction>	_MULTIPLY_NUM Simple math: multiplication.
static ExprFunc<String>	_PROPERTY The _PROPERTY function interrogates the dance engine's environment, as exposed by DanceState.property(String, String).
static ExprFunc<String>	_ROLL_PATTERN
static ExprFunc<String>	_SELECTION_PATTERN Check the order of the selected dancers within the given formation.
static ExprFunc<Fraction>	_SUBTRACT_NUM Simple math: subtraction.
static ExprFunc<String>	_SWEEP_PATTERN
static ExprFunc	LITERAL
static ExprFunc<Fraction>	NUM_DANCERS

Method Summary

static <T> T	evaluate(String atom, Class<T> type, DanceState ds, List<Expr> args) This method evaluates Expr nodes.
static <T> boolean	isConstant(String atom, Class<T> type, List<Expr> args) This method tells whether an Expr will result in a constant.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LITERAL

public static final ExprFunc LITERAL

_IF

public static final ExprFunc _IF

_APPLY

public static final ExprFunc _APPLY

_ADD_NUM

public static final ExprFunc<Fraction> _ADD_NUM

Simple math: addition.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _add num '2 '1)")
(Expr _add num '2 '1)
js> c.evaluate(fc, ds).toProperString()
3

_MULTIPLY_NUM

public static final ExprFunc<Fraction> _MULTIPLY_NUM

Simple math: multiplication.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _multiply num '3 '2)")
(Expr _multiply num '3 '2)
js> c.evaluate(fc, ds).toProperString()
6

_SUBTRACT_NUM

public static final ExprFunc<Fraction> _SUBTRACT_NUM

Simple math: subtraction.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _subtract num '3 '2)")
(Expr _subtract num '3 '2)
js> c.evaluate(fc, ds).toProperString()
1

_DIVIDE_NUM

public static final ExprFunc<Fraction> _DIVIDE_NUM

Simple math: division.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _divide num '3 '2)")
(Expr _divide num '3 '2)
js> c.evaluate(fc, ds).toProperString()
1 1/2

_MOD_NUM

public static final ExprFunc<Fraction> _MOD_NUM

Simple math: modulo.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _mod num '3/4 '1/2)")
(Expr _mod num '3/4 '1/2)
js> c.evaluate(fc, ds).toProperString()
1/4

_FLOOR

public static final ExprFunc<Fraction> _FLOOR

Simple math: return integer part of a fraction.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _floor '3 3/4)")
(Expr _floor '3 3/4)
js> c.evaluate(fc, ds).toProperString()
3
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _floor (Expr _subtract num '0 '3 3/4))")
(Expr _floor (Expr _subtract num '0 '3 3/4))
js> c.evaluate(fc, ds).toProperString()
-4

_FRACTION

public static final ExprFunc<Fraction> _FRACTION

Simple math: return fractional part of a number.

Tests:

js> ds = new DanceState(new DanceProgram(Program.C4), Formation.SQUARED_SET); undefined;
js> fc = java.lang.Class.forName('net.cscott.sdr.util.Fraction'); undefined
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _fraction '3 3/4)")
(Expr _fraction '3 3/4)
js> c.evaluate(fc, ds).toProperString()
3/4
js> // note that (floor(n) + fraction(n)) = n
js> c=net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _fraction (Expr _subtract num '0 '3 3/4))")
(Expr _fraction (Expr _subtract num '0 '3 3/4))
js> c.evaluate(fc, ds).toProperString()
1/4

NUM_DANCERS

public static final ExprFunc<Fraction> NUM_DANCERS

_ROLL_PATTERN

public static final ExprFunc<String> _ROLL_PATTERN

_SWEEP_PATTERN

public static final ExprFunc<String> _SWEEP_PATTERN

_FACING_PATTERN

public static final ExprFunc<String> _FACING_PATTERN

_COUPLE_NUM_PATTERN

public static final ExprFunc<String> _COUPLE_NUM_PATTERN

The _COUPLE_NUM_PATTERN is mostly for determining when we're "at home".

Tests:

Dancers in pattern are in "reading order":

js> let expr = net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _COUPLE NUM PATTERN)");
js> ds = new DanceState(new DanceProgram(Program.PLUS), Formation.SQUARED_SET); undefined
js> sc = java.lang.Class.forName("java.lang.String")
class java.lang.String
js> expr.evaluate(sc, ds)
33424211

_INOUT_PATTERN

public static final ExprFunc<String> _INOUT_PATTERN

Check whether dancers are facing "in" or "out" of the center of the formation. Dancers facing south or west in the top-right quadrant (positive x and y) are facing "in", dancers facing north or east in the top quadrant are facing "out". Where in/out direction can not be determined, this function uses an "x".

Tests:

js> FormationList = FormationList.js(this); undefined;
js> SD = StandardDancer; undefined
js> e = net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _INOUT PATTERN)");
(Expr _INOUT PATTERN)
js> f=FormationList.PARALLEL_RH_WAVES ; f.toStringDiagram()
^    v    ^    v

^    v    ^    v
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> e.evaluate(java.lang.Class.forName("java.lang.String"), ds);
oioiioio
js> f = FormationList.TRADE_BY; f.toStringDiagram()
^    ^

v    v

^    ^

v    v
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> e.evaluate(java.lang.Class.forName("java.lang.String"), ds);
ooiiiioo
js> f = Formation.SQUARED_SET ; f.toStringDiagram()
     3Gv  3Bv

4B>            2G<

4G>            2B<

     1B^  1G^
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> e.evaluate(java.lang.Class.forName("java.lang.String"), ds);
iiiiiiii
js> f = Formation.SQUARED_SET.rotate(ExactRotation.ONE_EIGHTH) ; f.toStringDiagram()
     4BQ       3GL

4GQ                 3BL



1B7                 2G`

     1G7       2B`
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> e.evaluate(java.lang.Class.forName("java.lang.String"), ds);
iiiiiiii
js> f = FormationList.SINGLE_STATIC_SQUARE ; f.toStringDiagram("|")
|     v
|
|>         <
|
|     ^
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> e.evaluate(java.lang.Class.forName("java.lang.String"), ds);
iiii
js> f = FormationList.THAR ; f.toStringDiagram("|")
|       <
|
|       >
|v    ^    v    ^
|       <
|
|       >
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> e.evaluate(java.lang.Class.forName("java.lang.String"), ds);
xxxxxxxx

_SELECTION_PATTERN

public static final ExprFunc<String> _SELECTION_PATTERN

Check the order of the selected dancers within the given formation.

Tests:

Dancers in pattern are in "reading order":

js> let expr = net.cscott.sdr.calls.ast.AstNode.valueOf(
  >           "(Expr _SELECTION PATTERN 'BOY)");
js> ds = new DanceState(new DanceProgram(Program.PLUS), Formation.SQUARED_SET); undefined
js> sc = java.lang.Class.forName("java.lang.String")
class java.lang.String
js> expr.evaluate(sc, ds)
_XX__XX_

Examples using the MATCH predicate:

js> FormationList = FormationList.js(this); undefined;
js> SD = StandardDancer; undefined
js> f = FormationList.RH_OCEAN_WAVE; f.toStringDiagram()
^    v    ^    v
js> // label those dancers
js> f= f.mapStd([SD.COUPLE_1_BOY, SD.COUPLE_1_GIRL,
  >              SD.COUPLE_3_BOY, SD.COUPLE_3_GIRL]); f.toStringDiagram()
1B^  1Gv  3B^  3Gv
js> ds = new DanceState(new DanceProgram(Program.PLUS), f); undefined;
js> function test(sel, pat) {
  >   let c = net.cscott.sdr.calls.ast.AstNode.valueOf(
  >           "(Expr MATCH (Expr _SELECTION PATTERN '"+sel+") '\""+pat+"\")");
  >    return PredicateList.valueOf(c.atom).evaluate(ds, c.args)
  > }
js> test('BOY', '____')
false
js> test('BOY', 'x_x_')
true
js> test('BOY', '_x_x')
false
js> test('CENTER', '_xx_')
true
js> test('HEAD', 'xxxx')
true
js> test('SIDE', '____')
true
js> test('COUPLE 1', 'xx__')
true
js> test('SIDE', '_xx_')
false
js> // wildcards
js> test('BOY', 'x...')
true

_PROPERTY

public static final ExprFunc<String> _PROPERTY

The _PROPERTY function interrogates the dance engine's environment, as exposed by DanceState.property(String, String).

Tests:

js> let expr = net.cscott.sdr.calls.ast.AstNode.valueOf("(Expr _PROPERTY 'foo 'bar)");
js> sc = java.lang.Class.forName("java.lang.String"); undefined
js> // default dance state contains no property mappings
js> ds = new DanceState(new DanceProgram(Program.PLUS), Formation.SQUARED_SET); undefined
js> expr.evaluate(sc, ds)
bar
js> // construct a simple property map
js> m = new java.util.HashMap(); m.put('foo', 'bat'); m.toString();
{foo=bat}
js> ds = new DanceState(new DanceProgram(Program.PLUS), Formation.SQUARED_SET, m); undefined
js> expr.evaluate(sc, ds)
bat

Method Detail

evaluate

public static <T> T evaluate(String atom,
                             Class<T> type,
                             DanceState ds,
                             List<Expr> args)
                  throws ExprFunc.EvaluationException

This method evaluates Expr nodes.

Throws:

ExprFunc.EvaluationException

isConstant

public static <T> boolean isConstant(String atom,
                                     Class<T> type,
                                     List<Expr> args)

This method tells whether an Expr will result in a constant.