f53376cea1
This adds a giant missing piece of the language: proper function values! It is lovely to now understand why early programming language designers didn't implement these, but a joy to now reap the benefits of them. In adding these, many other changes had to be made to get them to "fit" correctly. This improved the code and fixed a number of bugs. Unfortunately this touched many areas of the code, and since I was learning how to do all of this for the first time, I've squashed most of my work into a single commit. Some more information: * This adds over 70 new tests to verify the new functionality. * Functions, global variables, and classes can all be implemented natively in mcl and built into core packages. * A new compiler step called "Ordering" was added. It is called by the SetScope step, and determines statement ordering and shadowing precedence formally. It helped remove at least one bug and provided the additional analysis required to properly capture variables when implementing function generators and closures. * The type unification code was improved to handle the new cases. * Light copying of Node's allowed our function graphs to be more optimal and share common vertices and edges. For example, if two different closures capture a variable $x, they'll both use the same copy when running the function, since the compiler can prove if they're identical. * Some areas still need improvements, but this is ready for mainstream testing and use!
92 lines
2.8 KiB
Go
92 lines
2.8 KiB
Go
// Mgmt
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// Copyright (C) 2013-2019+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package util
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import (
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"fmt"
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"github.com/purpleidea/mgmt/lang/types"
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)
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// HasDuplicateTypes returns an error if the list of types is not unique.
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func HasDuplicateTypes(typs []*types.Type) error {
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// FIXME: do this comparison in < O(n^2) ?
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for i, ti := range typs {
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for j, tj := range typs {
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if i == j {
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continue // don't compare to self
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}
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if ti.Cmp(tj) == nil {
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return fmt.Errorf("duplicate type of %+v found", ti)
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}
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}
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}
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return nil
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}
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// FnMatch is run to turn a polymorphic, undetermined list of functions, into a
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// specific statically typed version. It is usually run after Unify completes.
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// It returns the index of the matched function.
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func FnMatch(typ *types.Type, fns []*types.FuncValue) (int, error) {
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// typ is the KindFunc signature we're trying to build...
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if typ == nil {
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return 0, fmt.Errorf("type of function must be specified")
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}
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if typ.Kind != types.KindFunc {
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return 0, fmt.Errorf("type must be of kind Func")
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}
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if typ.Out == nil {
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return 0, fmt.Errorf("return type of function must be specified")
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}
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// find typ in fns
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for ix, f := range fns {
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if f.T.HasVariant() {
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continue // match these if no direct matches exist
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}
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// FIXME: can we replace this by the complex matcher down below?
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if f.T.Cmp(typ) == nil {
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return ix, nil // found match at this index
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}
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}
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// match concrete type against our list that might contain a variant
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var found bool
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var index int
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for ix, f := range fns {
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_, err := typ.ComplexCmp(f.T)
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if err != nil {
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continue
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}
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if found { // already found one...
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// TODO: we *could* check that the previous duplicate is
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// equivalent, but in this case, it is really a bug that
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// the function author had by allowing ambiguity in this
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return 0, fmt.Errorf("duplicate match found for build type: %+v", typ)
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}
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found = true
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index = ix // found match at this index
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}
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// ensure there's only one match...
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if found {
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return index, nil // w00t!
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}
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return 0, fmt.Errorf("unable to find a compatible function for type: %+v", typ)
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}
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