parser: cleanup and simplify language parsing (#20185)

vlib/v/parser/fn.v

@@ -249,17 +249,8 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 	p.check(.key_fn)
 	comments << p.eat_comments()
 	p.open_scope()
-	// C. || JS.
-	mut language := ast.Language.v
 	language_tok_pos := p.tok.pos()
-	if p.tok.kind == .name && p.tok.lit == 'C' {
+	mut language := p.parse_language()
-		is_unsafe = !is_trusted
-		language = .c
-	} else if p.tok.kind == .name && p.tok.lit == 'JS' {
-		language = .js
-	} else if p.tok.kind == .name && p.tok.lit == 'WASM' {
-		language = .wasm
-	}
 	p.fn_language = language
 	if language != .v {
 		for fna in p.attrs {
@@ -274,9 +265,10 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			language_tok_pos)
 	}
 	if language != .v {
-		p.next()
-		p.check(.dot)
 		p.check_for_impure_v(language, language_tok_pos)
+		if language == .c {
+			is_unsafe = !is_trusted
+		}
 	}
 	// Receiver?
 	mut rec := ReceiverParsingInfo{
@@ -521,14 +513,11 @@ run them via `v file.v` instead',
 			language: language
 		})
 	} else {
-		if language == .c {
+		name = match language {
-			name = 'C.${name}'
+			.c { 'C.${name}' }
-		} else if language == .js {
+			.js { 'JS.${name}' }
-			name = 'JS.${name}'
+			.wasm { 'WASM.${name}' }
-		} else if language == .wasm {
+			else { p.prepend_mod(name) }
-			name = 'WASM.${name}'
-		} else {
-			name = p.prepend_mod(name)
 		}
 		if !p.pref.translated && language == .v {
 			if existing := p.table.fns[name] {

vlib/v/parser/parse_type.v

@@ -327,14 +327,11 @@ fn (mut p Parser) parse_type_with_mut(is_mut bool) ast.Type {
 
 // Parses any language indicators on a type.
 fn (mut p Parser) parse_language() ast.Language {
-	language := if p.tok.lit == 'C' {
+	language := match p.tok.lit {
-		ast.Language.c
+		'C' { ast.Language.c }
-	} else if p.tok.lit == 'JS' {
+		'JS' { ast.Language.js }
-		ast.Language.js
+		'WASM' { ast.Language.wasm }
-	} else if p.tok.lit == 'WASM' {
+		else { ast.Language.v }
-		ast.Language.wasm
-	} else {
-		ast.Language.v
 	}
 	if language != .v {
 		p.next()

vlib/v/parser/parser.v

@@ -2534,15 +2534,13 @@ fn (mut p Parser) name_expr() ast.Expr {
 			pos: type_pos
 		}
 	}
-	mut language := ast.Language.v
+	language := match p.tok.lit {
-	if p.tok.lit == 'C' {
+		'C' { ast.Language.c }
-		language = ast.Language.c
+		'JS' { ast.Language.js }
-		p.check_for_impure_v(language, p.tok.pos())
+		'WASM' { ast.Language.wasm }
-	} else if p.tok.lit == 'JS' {
+		else { ast.Language.v }
-		language = ast.Language.js
+	}
-		p.check_for_impure_v(language, p.tok.pos())
+	if language != .v {
-	} else if p.tok.lit == 'WASM' {
-		language = ast.Language.wasm
 		p.check_for_impure_v(language, p.tok.pos())
 	}
 	is_option := p.tok.kind == .question

vlib/v/parser/struct.v

@@ -25,19 +25,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 	} else {
 		p.check(.key_union)
 	}
-	language := if p.tok.lit == 'C' && p.peek_tok.kind == .dot {
+	language := p.parse_language()
-		ast.Language.c
-	} else if p.tok.lit == 'JS' && p.peek_tok.kind == .dot {
-		ast.Language.js
-	} else if p.tok.lit == 'WASM' && p.peek_tok.kind == .dot {
-		ast.Language.wasm
-	} else {
-		ast.Language.v
-	}
-	if language != .v {
-		p.next() // C || JS
-		p.next() // .
-	}
 	name_pos := p.tok.pos()
 	p.check_for_impure_v(language, name_pos)
 	if p.disallow_declarations_in_script_mode() {
@@ -522,17 +510,7 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 		p.next()
 	}
 	p.next() // `interface`
-	language := if p.tok.lit == 'C' && p.peek_tok.kind == .dot {
+	language := p.parse_language()
-		ast.Language.c
-	} else if p.tok.lit == 'JS' && p.peek_tok.kind == .dot {
-		ast.Language.js
-	} else {
-		ast.Language.v
-	}
-	if language != .v {
-		p.next() // C || JS | WASM
-		p.next() // .
-	}
 	name_pos := p.tok.pos()
 	p.check_for_impure_v(language, name_pos)
 	if p.disallow_declarations_in_script_mode() {