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Compound assign
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@@ -27,6 +27,10 @@ pub enum TokKind {
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gt
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ge
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assign
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plus_eq
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minus_eq
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star_eq
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slash_eq
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dotdot
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dotdotdot
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kw_fn
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@@ -172,18 +176,34 @@ fn (mut l Lexer) next() !Tok {
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}
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`+` {
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l.advance()
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if l.peek() == `=` {
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l.advance()
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return Tok{ kind: .plus_eq, lit: '+=', line: line }
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}
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return Tok{ kind: .plus, lit: '+', line: line }
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}
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`-` {
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l.advance()
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if l.peek() == `=` {
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l.advance()
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return Tok{ kind: .minus_eq, lit: '-=', line: line }
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}
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return Tok{ kind: .minus, lit: '-', line: line }
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}
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`*` {
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l.advance()
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if l.peek() == `=` {
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l.advance()
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return Tok{ kind: .star_eq, lit: '*=', line: line }
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}
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return Tok{ kind: .star, lit: '*', line: line }
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}
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`/` {
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l.advance()
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if l.peek() == `=` {
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l.advance()
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return Tok{ kind: .slash_eq, lit: '/=', line: line }
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}
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return Tok{ kind: .slash, lit: '/', line: line }
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}
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`%` {
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+48
-18
@@ -435,26 +435,56 @@ fn (mut p Parser) parse_stmt() !Stmt {
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} else {
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e = p.parse_postfix_tail(Expr{ kind: .ident, name: t.lit, line: t.line })!
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}
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if p.cur().kind == .assign {
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// assignment to an ident, an index, or a field
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p.advance()
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rhs := p.parse_expr()!
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match e.kind {
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.ident {
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return Stmt{ kind: .assign_stmt, target: e.name, expr: rhs, line: t.line }
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}
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.index {
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return Stmt{ kind: .index_assign, base: *e.left, idx: *e.right, expr: rhs, line: t.line }
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}
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.field {
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return Stmt{ kind: .field_assign, base: *e.left, target: e.name, expr: rhs, line: t.line }
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}
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else {
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return error('cannot assign to this expression (line ${t.line})')
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}
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if p.cur().kind == .assign {
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// assignment to an ident, an index, or a field
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p.advance()
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rhs := p.parse_expr()!
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match e.kind {
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.ident {
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return Stmt{ kind: .assign_stmt, target: e.name, expr: rhs, line: t.line }
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}
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.index {
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return Stmt{ kind: .index_assign, base: *e.left, idx: *e.right, expr: rhs, line: t.line }
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}
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.field {
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return Stmt{ kind: .field_assign, base: *e.left, target: e.name, expr: rhs, line: t.line }
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}
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else {
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return error('cannot assign to this expression (line ${t.line})')
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}
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}
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return Stmt{ kind: .expr_stmt, expr: e, line: t.line }
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}
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// compound assignment: x += expr, a[i] += expr, a.b += expr
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if p.cur().kind == .plus_eq || p.cur().kind == .minus_eq || p.cur().kind == .star_eq || p.cur().kind == .slash_eq {
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op_tok := p.advance()
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rhs := p.parse_expr()!
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bin_op := match op_tok.kind {
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.plus_eq { TokKind.plus }
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.minus_eq { TokKind.minus }
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.star_eq { TokKind.star }
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.slash_eq { TokKind.slash }
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else { return error('unexpected compound operator (line ${t.line})') }
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}
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// desugar: LHS op= RHS → LHS = LHS op RHS
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match e.kind {
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.ident {
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full_rhs := bin_node(bin_op, e, rhs, op_tok.line)
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return Stmt{ kind: .assign_stmt, target: e.name, expr: full_rhs, line: t.line }
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}
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.index {
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full_rhs := bin_node(bin_op, e, rhs, op_tok.line)
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return Stmt{ kind: .index_assign, base: *e.left, idx: *e.right, expr: full_rhs, line: t.line }
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}
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.field {
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full_rhs := bin_node(bin_op, e, rhs, op_tok.line)
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return Stmt{ kind: .field_assign, base: *e.left, target: e.name, expr: full_rhs, line: t.line }
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}
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else {
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return error('cannot use compound assignment on this expression (line ${t.line})')
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}
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}
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}
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return Stmt{ kind: .expr_stmt, expr: e, line: t.line }
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}
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.kw_print, .kw_println {
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p.advance()
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