AST to SExpression...sexah!

support/parser.lua

@@ -77,7 +77,7 @@ end
 
 function parse( inCodeString )
 	local theASTRoot = parseToAST( inCodeString )
-	return codeFromAST( theASTRoot.program )
+	return codeFromAST( theASTRoot )
 end
 
 function parseToAST( inCodeString )
@@ -94,20 +94,19 @@ end
 
 function codeFromAST( inASTNode )
 	local theResult
-	if inASTNode.type == "program" then
-		theResult = runtime.createList( )
-		for i,theChildNode in ipairs( inASTNode ) do
-			runtime.appendListItem( theResult, codeFromAST( theChildNode ) )
+	if inASTNode.type == "program" or inASTNode.type == "expression" then
+		local theHead
+		for i=#inASTNode,1,-1 do
+			theHead = runtime.join( codeFromAST( inASTNode[ i ] ), theHead )
 		end
+		theHead.quotedFlag = inASTNode.quotedFlag
+		theResult = theHead
 
-	elseif inASTNode.type == "expression" then
-		theResult = runtime.createList{ quotedFlag = inASTNode.quotedFlag }
-		for i,theChildNode in ipairs( inASTNode ) do
-			runtime.appendListItem( theResult, codeFromAST( theChildNode ) )
-		end
-
-	else -- symbol, number, string
-		theResult = runtime[ inASTNode.type ][ inASTNode.value ]
+	elseif inASTNode.type == "symbol" then
+		theResult = runtime.createValue( inASTNode.type, inASTNode.value, inASTNode.quotedFlag )
+
+	else -- number, string
+		theResult = inASTNode.value
 
 	end
 

support/runtime.lua

@@ -0,0 +1,15 @@
+module( 'runtime', package.seeall )
+
+function join( inHeadValue, inTailValue )
+	return { head=inHeadValue, tail=inTailValue }
+end
+
+function createValue( inType, inValue, inQuotedFlag )
+	local theResult
+	if inType == 'symbol' then
+		theResult = { symbol=inValue, quotedFlag=inQuotedFlag }
+	else
+		error( "Unrecognized value type '"..inType.."'" )
+	end
+	return theResult
+end

test/test_parser.lua

@@ -46,4 +46,85 @@ function test02_ast_results( )
 	)
 end
 
+function test03_codeFromAST( )
+	local theCode = "[foo bar]"
+	local theProgram = parser.parse( theCode )
+	assertTableEquals( theProgram, {
+	  head = {
+	    head = {
+	      symbol = "foo"
+	    },
+	    tail = {
+	      head = {
+	        symbol = "bar"
+	      },
+	    }
+	  },
+	} )
+
+	local theCode = "[foo 'bar 17 \"whee\"]"
+	local theProgram = parser.parse( theCode )
+	assertTableEquals( theProgram, {
+	  head = {
+	    head = {
+	      symbol = "foo"
+	    },
+	    tail = {
+	      head = {
+	        symbol = "bar",
+	        quotedFlag = true
+	      },
+	      tail = {
+	      	head = 17,
+	      	tail = {
+	      		head = "whee"
+	      	}
+	      }
+	    }
+	  },
+	} )
+
+	local theCode = "[foo [bar]] [jim]"
+	local theProgram = parser.parse( theCode )
+	assertTableEquals( theProgram, {
+	  head = {
+	    head = {
+	      symbol = "foo"
+	    },
+	    tail = {
+	    	head = {
+	    		head = {
+	    			symbol = "bar"
+	    		}
+	    	}
+	    }
+	  },
+	  tail = {
+	  	head = {
+	  		head = {
+		  		symbol = "jim"  			
+	  		}
+	  	}
+	  }
+	} )
+
+	local theCode = [===[
+		[define map inFunc inList
+			[pair [inFunc [head inList]]
+				[map 'inFunc [rest inList]]
+			]
+		]
+		[define square x 
+			[* x x]
+		]
+		[print [map square '[1 2 3 4 5]]]
+	]===]
+
+	local theProgram = parser.parse( theCode )	
+	-- assertTableEquals( theProgram, {
+	-- 	head={}
+	-- 	rest={}
+	-- })
+end
+
 runTests{ useHTML = true }