Modify Expression constructor API to use varargs

kiwi.lua

@@ -532,7 +532,7 @@ end
 do
    --- Expressions are a sum of terms with an added constant.
    ---@class kiwi.Expression: ffi.cdata*
-   ---@overload fun(terms: kiwi.Term[], constant: number?): kiwi.Expression
+   ---@overload fun(constant: number, ...: kiwi.Term): kiwi.Expression
    ---@field constant number
    ---@field package term_count number
    ---@field package terms_ ffi.cdata*
@@ -637,17 +637,16 @@ do
       __index = Expression_cls,
    }
 
-   function Expression_mt.__new(T, terms, constant)
-      local term_count = terms and #terms or 0
+   function Expression_mt.__new(T, constant, ...)
+      local term_count = select("#", ...)
       local e = ffi_gc(ffi_new(T, term_count), ckiwi.kiwi_expression_del_vars) --[[@as kiwi.Expression]]
       e.term_count = term_count
-      e.constant = constant or 0.0
-      if terms then
-         for i, t in ipairs(terms) do
-            local dt = e.terms_[i - 1] --[[@as kiwi.Term]]
-            dt.var = ckiwi.kiwi_var_clone(t.var)
-            dt.coefficient = t.coefficient
-         end
+      e.constant = constant
+      for i = 1, term_count do
+         local t = select(i, ...)
+         local dt = e.terms_[i - 1] --[[@as kiwi.Term]]
+         dt.var = ckiwi.kiwi_var_clone(t.var)
+         dt.coefficient = t.coefficient
       end
       return e
    end

spec/constraint_spec.lua

@@ -42,7 +42,7 @@ describe("Constraint", function()
          c = kiwi.Constraint(lhs / 2, nil, "LE", kiwi.strength.MEDIUM)
          assert.equal("0.5 foo + 0.5 <= 0 | medium", tostring(c))
 
-         c = kiwi.Constraint(lhs, kiwi.Expression(nil, 3), "GE", kiwi.strength.WEAK)
+         c = kiwi.Constraint(lhs, kiwi.Expression(3), "GE", kiwi.strength.WEAK)
          assert.equal("1 foo + -2 >= 0 | weak", tostring(c))
       end)
 
@@ -68,7 +68,7 @@ describe("Constraint", function()
       end)
       it("combines lhs and rhs", function()
          local v2 = kiwi.Var("bar")
-         local rhs = kiwi.Expression({ 5 * v2, 3 * v }, 3)
+         local rhs = kiwi.Expression(3, 5 * v2, 3 * v)
          local c = kiwi.Constraint(lhs, rhs)
 
          local e = c:expression()