Add parsing of elseif and else

examples/test.lua

@@ -1,49 +1,10 @@
-global b = 5
 
-function add(x)
-    return function (y)
-        x = x + 1
-        b = b + 1
-        return x + y, 1, 2, b
-    end
+local test = 10
+if test == 10 then
+    print("first")
+elseif test == 11 then
+    print("second")
+else
+    print("third")
 end
-
-function min(x, y)
-    local m = x
-    if y < x then
-        m = y
-    end
-    return m
-end
-
-
-function f(x, ...)
-    local b = {10, ..., add(10)(15)}
-    return x + 5, b
-end
-
-global sometable = {}
-sometable["hello"] = { 100, 150, add(10)(15) }
-print(#sometable["hello"])
-sometable["hello"].there = "my dude"
-print(sometable.hello.there)
-
-print(max(11.12345, 9))
-print(add(10)(15))
-print(add(10)(15))
-print(b)
-print(min(11, 9))
-print(10 - 15)
-print("hello there!")
-print(true or 0)
-
-global value, table = f(10, 11, 12)
-
-print("hello")
-for i=1,#table do
-    print(table[i])
-    if i > 2 then
-        goto test
-    end
-end
-::test::
+print("after")

src/ast.rs

@@ -234,7 +234,12 @@ impl Parse for Block {
 
         while !matches!(
             stream.peek(),
-            Some(Token::Keyword(Keyword::End) | Token::Eof)
+            Some(
+                Token::Keyword(Keyword::End)
+                    | Token::Keyword(Keyword::ElseIf)
+                    | Token::Keyword(Keyword::Else)
+                    | Token::Eof
+            )
         ) {
             statements.push(stream.parse()?);
         }
@@ -254,7 +259,11 @@ pub enum Statement {
         ExpressionList,
     ),
     Return(ExpressionList),
-    If(Node<Expression>, Block),
+    If {
+        if_part: (Node<Expression>, Block),
+        elif: Vec<(Node<Expression>, Block)>,
+        else_block: Block,
+    },
     Expression(Node<Expression>),
     NumericalFor(
         Node<String>,
@@ -296,11 +305,35 @@ impl Parse for Statement {
             Ok(Statement::Return(stream.parse()?))
         } else if peeked == Some(Token::Keyword(Keyword::If)) {
             stream.next(); // Consume if
-            let cond = stream.parse()?;
+            let if_cond = stream.parse()?;
             stream.expect(Token::Keyword(Keyword::Then))?;
-            let then = stream.parse()?;
+            let if_block = stream.parse()?;
+
+            let mut elif = Vec::new();
+            while let Some(Token::Keyword(Keyword::ElseIf)) = stream.peek() {
+                stream.next();
+                let elif_cond = stream.parse()?;
+                stream.expect(Token::Keyword(Keyword::Then))?;
+                let elif_block = stream.parse()?;
+                elif.push((elif_cond, elif_block));
+            }
+
+            let else_block = if let Some(Token::Keyword(Keyword::Else)) = stream.peek() {
+                stream.next();
+                stream.parse()?
+            } else {
+                Block {
+                    statements: Vec::new(),
+                    _meta: Metadata::empty(),
+                }
+            };
+
             stream.expect(Token::Keyword(Keyword::End))?;
-            Ok(Self::If(cond, then))
+            Ok(Self::If {
+                if_part: (if_cond, if_block),
+                elif: elif,
+                else_block,
+            })
         } else if let Some(Token::Keyword(Keyword::Local | Keyword::Global)) = peeked {
             let access_modifier = match stream.next() {
                 Some(Token::Keyword(Keyword::Local)) => AccessModifier::Local,

src/compile.rs

@@ -187,10 +187,21 @@ impl Statement {
                 }
                 constants
             }
-            Statement::If(cond, then) => {
+            Statement::If {
+                if_part,
+                elif,
+                else_block,
+            } => {
                 let mut constants = HashSet::new();
-                constants.extend(cond.kind.find_constants(scope));
-                constants.extend(then.find_constants(scope, Vec::new()));
+                constants.extend(if_part.0.kind.find_constants(scope));
+                constants.extend(if_part.1.find_constants(scope, Vec::new()));
+
+                for (cond, block) in elif {
+                    constants.extend(cond.kind.find_constants(scope));
+                    constants.extend(block.find_constants(scope, Vec::new()));
+                }
+
+                constants.extend(else_block.find_constants(scope, Vec::new()));
                 constants
             }
             Statement::Expression(expr) => expr.kind.find_constants(scope),
@@ -397,8 +408,12 @@ impl Statement {
                     },
                 )));
             }
-            Statement::If(expr, block) => {
-                let (instr, regs) = expr.kind.compile(state, scope, Some(1));
+            Statement::If {
+                if_part,
+                elif,
+                else_block,
+            } => {
+                let (instr, regs) = if_part.0.kind.compile(state, scope, Some(1));
                 instructions.extend(instr);
 
                 let local = scope.register_counter.next();
@@ -408,7 +423,7 @@ impl Statement {
                     0,
                 )));
 
-                let block_instructions = block.compile(state, scope);
+                let block_instructions = if_part.1.compile(state, scope);
                 instructions.push(PreInstr::Instr(Instruction::Jmp(
                     block_instructions.len() as i32
                 )));

src/token_stream/lexer.rs

@@ -15,6 +15,8 @@ pub enum Keyword {
     Global,
     Return,
     If,
+    ElseIf,
+    Else,
     Then,
     True,
     False,
@@ -35,6 +37,8 @@ impl Keyword {
             "global" => Keyword::Global,
             "return" => Keyword::Return,
             "if" => Keyword::If,
+            "elseif" => Keyword::ElseIf,
+            "else" => Keyword::Else,
             "then" => Keyword::Then,
             "true" => Keyword::True,
             "false" => Keyword::False,
@@ -58,6 +62,8 @@ impl ToString for Keyword {
             Keyword::Global => "global",
             Keyword::Return => "return",
             Keyword::If => "if",
+            Keyword::ElseIf => "elif",
+            Keyword::Else => "else",
             Keyword::Then => "then",
             Keyword::True => "true",
             Keyword::False => "false",