Merge pull request 'Add dereference parsing' (#17) from parse-dereferences into main

Reviewed-on: arf/arf#17

parser/argument.go

@@ -3,8 +3,6 @@ package parser
 import "git.tebibyte.media/arf/arf/lexer"
 import "git.tebibyte.media/arf/arf/infoerr"
 
-// TODO: add support for dereferences and subscripts
-
 var validArgumentStartTokens = []lexer.TokenKind {
 	lexer.TokenKindName,
 	
@@ -14,6 +12,7 @@ var validArgumentStartTokens = []lexer.TokenKind {
 	lexer.TokenKindString,
 	
 	lexer.TokenKindLBracket,
+	lexer.TokenKindLBrace,
 	lexer.TokenKindLParen,
 }
 
@@ -81,6 +80,10 @@ func (parser *ParsingOperation) parseArgument () (argument Argument, err error)
 		argument.kind = ArgumentKindPhrase
 		argument.value, err = parser.parseArgumentLevelPhrase()
 
+	case lexer.TokenKindLBrace:
+		argument.kind = ArgumentKindDereference
+		argument.value, err = parser.parseDereference()
+
 	case lexer.TokenKindLParen:
 		argument.kind = ArgumentKindList
 		argument.value, err = parser.parseList()

parser/dereference.go

@@ -0,0 +1,31 @@
+package parser
+
+import "git.tebibyte.media/arf/arf/lexer"
+
+func (parser *ParsingOperation) parseDereference () (
+	dereference Dereference,
+	err error,
+) {
+	err = parser.expect(lexer.TokenKindLBrace)
+	if err != nil { return }
+	dereference.location = parser.token.Location()
+	
+	// parse the value we are dereferencing
+	err = parser.nextToken(validArgumentStartTokens...)
+	if err != nil { return }
+	dereference.argument, err = parser.parseArgument()
+	if err != nil { return }
+
+	// if there is an offset, parse it
+	err = parser.expect(lexer.TokenKindUInt, lexer.TokenKindRBrace)
+	if err != nil { return }
+	if parser.token.Is(lexer.TokenKindUInt) {
+		dereference.offset = parser.token.Value().(uint64)
+	}
+	
+	err = parser.nextToken(lexer.TokenKindRBrace)
+	if err != nil { return }
+	err = parser.nextToken()
+	if err != nil { return }
+	return
+}

parser/func_test.go

@@ -105,5 +105,13 @@ func ro hDataInit
 	[= y:{Int} [loc x]]
 	[= z:Int:8 (398 9 2309 983 -2387 478 555 123)]
 	[= bird:Bird ((99999) 324)]
+func ro iDereference
+	> x:{Int}
+	> y:{Int ..}
+	> z:Int:4
+	---
+	[= b:Int {x}]
+	[= c:Int {y 4}]
+	[= d:Int {z 3}]
 `, test)
 }

parser/tree-tostring.go

@@ -134,6 +134,9 @@ func (argument Argument) ToString (indent int, breakLine bool) (output string) {
 	case ArgumentKindList:
 		output += argument.value.(List).ToString(indent, breakLine)
 
+	case ArgumentKindDereference:
+		output += argument.value.(Dereference).ToString(indent)
+	
 	case ArgumentKindIdentifier:
 		output += doIndent (
 			indent,
@@ -276,6 +279,16 @@ func (behavior FaceBehavior) ToString (indent int) (output string) {
 	return
 }
 
+func (dereference Dereference) ToString (indent int) (output string) {
+	output += "{"
+	output += dereference.argument.ToString(indent, false)
+	if dereference.offset != 0 {
+		output += fmt.Sprint(" ", dereference.offset)
+	}
+	output += "}"
+	return
+}
+
 func (phrase Phrase) ToString (indent int, ownLine bool) (output string) {
 	if ownLine {
 		output += doIndent(indent)

parser/tree.go

@@ -97,10 +97,8 @@ const (
 	ArgumentKindList
 
 	// {name}
-	ArgumentKindDereference
-	
 	// {name 23}
-	ArgumentKindSubscript
+	ArgumentKindDereference
 
 	// name.name
 	// name.name.name
@@ -220,6 +218,15 @@ type FaceSection struct {
 	FaceBehavior
 }
 
+// Dereference represents a pointer dereference or array subscript.
+type Dereference struct {
+	locatable
+	valuable
+
+	// if a simple dereference was parsed, this should just be zero.
+	offset uint64
+}
+
 // PhraseKind determines what semantic role a phrase plays.
 type PhraseKind int
 

tests/parser/func/main.arf

@@ -132,3 +132,12 @@ func ro hDataInit
 	= bird:Bird (
 		(99999)
 		324)
+
+func ro iDereference
+	> x:{Int}
+	> y:{Int ..}
+	> z:Int:4
+	---
+	= b:Int {x}
+	= c:Int {y 4}
+	= d:Int {z 3}