Variable coupling

README.md

@@ -31,6 +31,9 @@ ls line: two
 one more time: two
 one more time: three
 end: one
+one - un
+two - deux
+three - trois
 onE
 two
 thrEE
@@ -155,6 +158,22 @@ cleanup( function() {
 } ) ;
 ```
 
+should iterate through a variable as a list using coupled variable substitution.
+
+```js
+cleanup( function() {
+
+	var book = new spellcast.Book( fs.readFileSync( 'spellbook' ).toString() ) ;
+
+	book.cast( 'foreach-coupled' , function( error )
+	{
+		expect( error ).not.ok() ;
+		expect( getCastedLog( 'foreach-coupled' ) ).to.be( 'one - un\ntwo - deux\nthree - trois\n' ) ;
+		done() ;
+	} ) ;
+} ) ;
+```
+
 <a name="transmute-block"></a>
 # 'transmute' block
 should execute a regular expression to a variable as a list.

bdd-spec.md

@@ -13,6 +13,9 @@ ls line: two
 one more time: two
 one more time: three
 end: one
+one - un
+two - deux
+three - trois
 onE
 two
 thrEE
@@ -137,6 +140,22 @@ cleanup( function() {
 } ) ;
 ```
 
+should iterate through a variable as a list using coupled variable substitution.
+
+```js
+cleanup( function() {
+
+	var book = new spellcast.Book( fs.readFileSync( 'spellbook' ).toString() ) ;
+
+	book.cast( 'foreach-coupled' , function( error )
+	{
+		expect( error ).not.ok() ;
+		expect( getCastedLog( 'foreach-coupled' ) ).to.be( 'one - un\ntwo - deux\nthree - trois\n' ) ;
+		done() ;
+	} ) ;
+} ) ;
+```
+
 <a name="transmute-block"></a>
 # 'transmute' block
 should execute a regular expression to a variable as a list.

format.md

@@ -17,6 +17,7 @@ When a variable is encountered, it is substituted by its string value.
 List of blocks that supports formula:
 * *scroll*'s command, when: at execution of each command
 * *scroll*'s *write-formula* argument
+* *scroll*'s *only-index* argument
 
 TODOC: list formula
 

lib/spellcast.js

@@ -822,7 +822,7 @@ spellcast.Book.prototype.castSummon = function castSummon( summon , castExecutio
 
 spellcast.Book.prototype.castScroll = function castScroll( scroll , castExecution , callback )
 {
-	var plan , splitter , self = this ;
+	var plan , self = this ;
 
 	plan = async
 		.map( scroll.shellCommands , this.execShellCommand.bind( this , castExecution , scroll.args ) )
@@ -844,17 +844,48 @@ spellcast.Book.prototype.castScroll = function castScroll( scroll , castExecutio
 		else { scroll.args['write-formula'] = this.variableSubstitution( scroll.args['write-formula'] ) ; }
 	}
 
+	// Perform variable substitution on only-index's argument
+	if ( scroll.args['only-index'] && typeof scroll.args['only-index'] === 'string' )
+	{
+		scroll.args['only-index'] = this.variableSubstitution( scroll.args['only-index'] ) ;
+	}
+
 	// Let's exec the plan and process the final outcome!
 
 	plan.exec( function( error , outputMap ) {
 
+		var splitter , splitted , formula ;
+
 		if ( error ) { callback( error ) ; return ; }
 
 		if ( scroll.args['write-formula'] )
 		{
+			formula = scroll.args['write-formula'] ;
 			splitter = scroll.args.splitter || '\n' ;
-			self.formula[ scroll.args['write-formula'] ] = outputMap.join( '' ).trim().split( splitter ) ;
-			Object.defineProperty( self.formula[ scroll.args['write-formula'] ] , 'index' , { value: 0 , writable: true } ) ;
+			splitted = outputMap.join( '' ).trim().split( splitter ) ;
+
+			if ( scroll.args['only-index'] )
+			{
+				if ( ! self.formula[ formula ] )
+				{
+					self.formula[ formula ] = [] ;
+					Object.defineProperty( self.formula[ formula ] , 'index' , { value: 0 , writable: true } ) ;
+				}
+
+				if ( typeof scroll.args['only-index'] === 'string' )
+				{
+					self.formula[ formula ][ parseInt( scroll.args['only-index'] ) ] = splitted[ 0 ] ;
+				}
+				else
+				{
+					self.formula[ formula ][ self.formula[ formula ].index ] = splitted[ 0 ] ;
+				}
+			}
+			else
+			{
+				self.formula[ formula ] = splitted ;
+				Object.defineProperty( self.formula[ formula ] , 'index' , { value: 0 , writable: true } ) ;
+			}
 
 			/*
 			console.log( "outputMap:" , outputMap[0] ) ;
@@ -974,10 +1005,35 @@ spellcast.Book.prototype.variableSubstitution = function variableSubstitution( i
 {
 	var output , self = this ;
 
-	output = input.replace( /\$\{([^\s\}]+)\}/g , function() {
-		var substitute = self.formula[ arguments[ 1 ] ] ;
+	output = input.replace( /\$\{([0-9a-zA-Z_-]+)(:([0-9a-zA-Z_-]+))?\}/g , function() {
+		var index , thirdParty , substitute = self.formula[ arguments[ 1 ] ] ;
+
 		if ( substitute === undefined ) { return '' ; }
-		return substitute[ substitute.index ] ;
+
+		if ( arguments[ 3 ] )
+		{
+			// Find a specific index
+
+			if ( arguments[ 3 ].match( /^[0-9]+$/ ) )
+			{
+				// This is a fixed numeric index
+				index = parseInt( arguments[ 3 ] ) ;
+			}
+			else
+			{
+				// Get the numeric index of a third party formula
+				thirdParty = self.formula[ arguments[ 3 ] ] ;
+				if ( thirdParty === undefined ) { return '' ; }
+				index = thirdParty.index ;
+			}
+		}
+		else
+		{
+			// Normal substitution mode: replace by the variable current index
+			index = substitute.index ;
+		}
+
+		return substitute[ index ] ;
 	} ) ;
 
 	return output ;

test/spellbook

@@ -3,6 +3,7 @@ formula
 	alert:bob
 	blah:blih
 	list:one,two,three
+	list-fr:un,deux,trois
 
 
 
@@ -27,6 +28,11 @@ formula
 	scroll
 		echo end: ${list}
 
+.foreach-coupled
+	foreach list
+		scroll
+			echo ${list} - ${list-fr:list}
+
 .transmute
 	transmute list
 		/e/g

test/spellcast-test.js

@@ -251,6 +251,21 @@ describe( "'foreach' block" , function() {
 			} ) ;
 		} ) ;
 	} ) ;
+
+	it( "should iterate through a variable as a list using coupled variable substitution" , function( done ) {
+
+		cleanup( function() {
+
+			var book = new spellcast.Book( fs.readFileSync( 'spellbook' ).toString() ) ;
+
+			book.cast( 'foreach-coupled' , function( error )
+			{
+				expect( error ).not.ok() ;
+				expect( getCastedLog( 'foreach-coupled' ) ).to.be( 'one - un\ntwo - deux\nthree - trois\n' ) ;
+				done() ;
+			} ) ;
+		} ) ;
+	} ) ;
 } ) ;