b19583e7d3
This is an initial implementation of the mgmt language. It is a declarative (immutable) functional, reactive, domain specific programming language. It is intended to be a language that is: * safe * powerful * easy to reason about With these properties, we hope this language, and the mgmt engine will allow you to model the real-time systems that you'd like to automate. This also includes a number of other associated changes. Sorry for the large size of this patch.
563 lines
18 KiB
Go
563 lines
18 KiB
Go
// Mgmt
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// Copyright (C) 2013-2018+ 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 unification // TODO: can we put this solver in a sub-package?
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import (
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"fmt"
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"github.com/purpleidea/mgmt/lang/interfaces"
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"github.com/purpleidea/mgmt/lang/types"
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errwrap "github.com/pkg/errors"
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)
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const (
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// Name is the prefix for our solver log messages.
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Name = "solver: simple"
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)
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// SimpleInvariantSolverLogger is a wrapper which returns a
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// SimpleInvariantSolver with the log parameter of your choice specified. The
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// result satisfies the correct signature for the solver parameter of the
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// Unification function.
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func SimpleInvariantSolverLogger(logf func(format string, v ...interface{})) func([]interfaces.Invariant) (*InvariantSolution, error) {
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return func(invariants []interfaces.Invariant) (*InvariantSolution, error) {
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return SimpleInvariantSolver(invariants, logf)
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}
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}
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// SimpleInvariantSolver is an iterative invariant solver for AST expressions.
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// It is intended to be very simple, even if it's computationally inefficient.
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func SimpleInvariantSolver(invariants []interfaces.Invariant, logf func(format string, v ...interface{})) (*InvariantSolution, error) {
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logf("%s: invariants:", Name)
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for i, x := range invariants {
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logf("invariant(%d): %T: %s", i, x, x)
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}
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solved := make(map[interfaces.Expr]*types.Type)
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equalities := []interfaces.Invariant{}
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exclusives := []*ExclusiveInvariant{}
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// iterate through all invariants, flattening and sorting the list...
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for _, x := range invariants {
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switch invariant := x.(type) {
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case *EqualsInvariant:
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equalities = append(equalities, invariant)
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case *EqualityInvariant:
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equalities = append(equalities, invariant)
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case *EqualityInvariantList:
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// de-construct this list variant into a series
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// of equality variants so that our solver can
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// be implemented more simply...
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if len(invariant.Exprs) < 2 {
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return nil, fmt.Errorf("list invariant needs at least two elements")
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}
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for i := 0; i < len(invariant.Exprs)-1; i++ {
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invar := &EqualityInvariant{
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Expr1: invariant.Exprs[i],
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Expr2: invariant.Exprs[i+1],
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}
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equalities = append(equalities, invar)
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}
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case *EqualityWrapListInvariant:
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equalities = append(equalities, invariant)
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case *EqualityWrapMapInvariant:
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equalities = append(equalities, invariant)
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case *EqualityWrapStructInvariant:
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equalities = append(equalities, invariant)
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case *EqualityWrapFuncInvariant:
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equalities = append(equalities, invariant)
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// contains a list of invariants which this represents
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case *ConjunctionInvariant:
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for _, invar := range invariant.Invariants {
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equalities = append(equalities, invar)
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}
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case *ExclusiveInvariant:
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// these are special, note the different list
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if len(invariant.Invariants) > 0 {
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exclusives = append(exclusives, invariant)
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}
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case *AnyInvariant:
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equalities = append(equalities, invariant)
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default:
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return nil, fmt.Errorf("unknown invariant type: %T", x)
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}
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}
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listPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
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mapPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
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structPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
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funcPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
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logf("%s: starting loop with %d equalities", Name, len(equalities))
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// run until we're solved, stop consuming equalities, or type clash
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for {
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logf("%s: iterate...", Name)
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if len(equalities) == 0 && len(exclusives) == 0 {
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break // we're done, nothing left
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}
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used := []int{}
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for i, x := range equalities {
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logf("%s: match(%T): %+v", Name, x, x)
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// TODO: could each of these cases be implemented as a
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// method on the Invariant type to simplify this code?
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switch eq := x.(type) {
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// trivials
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case *EqualsInvariant:
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typ, exists := solved[eq.Expr]
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if !exists {
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solved[eq.Expr] = eq.Type // yay, we learned something!
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used = append(used, i) // mark equality as used up
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logf("%s: solved trivial equality", Name)
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continue
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}
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// we already specified this, so check the repeat is consistent
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if err := typ.Cmp(eq.Type); err != nil {
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// this error shouldn't happen unless we purposefully
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// try to trick the solver, or we're in a recursive try
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with equals")
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}
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used = append(used, i) // mark equality as duplicate
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logf("%s: duplicate trivial equality", Name)
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continue
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// partials
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case *EqualityWrapListInvariant:
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if _, exists := listPartials[eq.Expr1]; !exists {
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listPartials[eq.Expr1] = make(map[interfaces.Expr]*types.Type)
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}
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if typ, exists := solved[eq.Expr1]; exists {
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// wow, now known, so tell the partials!
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listPartials[eq.Expr1][eq.Expr2Val] = typ.Val
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}
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// can we add to partials ?
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for _, y := range []interfaces.Expr{eq.Expr2Val} {
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typ, exists := solved[y]
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if !exists {
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continue
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}
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t, exists := listPartials[eq.Expr1][y]
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if !exists {
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listPartials[eq.Expr1][y] = typ // learn!
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continue
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}
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with partial list val")
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}
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}
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// can we solve anything?
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var ready = true // assume ready
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typ := &types.Type{
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Kind: types.KindList,
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}
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valTyp, exists := listPartials[eq.Expr1][eq.Expr2Val]
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if !exists {
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ready = false // nope!
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} else {
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typ.Val = valTyp // build up typ
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}
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if ready {
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if t, exists := solved[eq.Expr1]; exists {
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with list")
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}
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}
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// sub checks
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if t, exists := solved[eq.Expr2Val]; exists {
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if err := t.Cmp(typ.Val); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with list val")
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}
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}
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solved[eq.Expr1] = typ // yay, we learned something!
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solved[eq.Expr2Val] = typ.Val // yay, we learned something!
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used = append(used, i) // mark equality as used up
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logf("%s: solved list wrap partial", Name)
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continue
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}
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case *EqualityWrapMapInvariant:
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if _, exists := mapPartials[eq.Expr1]; !exists {
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mapPartials[eq.Expr1] = make(map[interfaces.Expr]*types.Type)
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}
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if typ, exists := solved[eq.Expr1]; exists {
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// wow, now known, so tell the partials!
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mapPartials[eq.Expr1][eq.Expr2Key] = typ.Key
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mapPartials[eq.Expr1][eq.Expr2Val] = typ.Val
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}
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// can we add to partials ?
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for _, y := range []interfaces.Expr{eq.Expr2Key, eq.Expr2Val} {
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typ, exists := solved[y]
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if !exists {
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continue
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}
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t, exists := mapPartials[eq.Expr1][y]
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if !exists {
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mapPartials[eq.Expr1][y] = typ // learn!
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continue
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}
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with partial map key/val")
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}
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}
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// can we solve anything?
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var ready = true // assume ready
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typ := &types.Type{
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Kind: types.KindMap,
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}
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keyTyp, exists := mapPartials[eq.Expr1][eq.Expr2Key]
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if !exists {
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ready = false // nope!
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} else {
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typ.Key = keyTyp // build up typ
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}
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valTyp, exists := mapPartials[eq.Expr1][eq.Expr2Val]
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if !exists {
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ready = false // nope!
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} else {
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typ.Val = valTyp // build up typ
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}
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if ready {
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if t, exists := solved[eq.Expr1]; exists {
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with map")
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}
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}
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// sub checks
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if t, exists := solved[eq.Expr2Key]; exists {
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if err := t.Cmp(typ.Key); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with map key")
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}
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}
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if t, exists := solved[eq.Expr2Val]; exists {
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if err := t.Cmp(typ.Val); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with map val")
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}
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}
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solved[eq.Expr1] = typ // yay, we learned something!
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solved[eq.Expr2Key] = typ.Key // yay, we learned something!
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solved[eq.Expr2Val] = typ.Val // yay, we learned something!
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used = append(used, i) // mark equality as used up
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logf("%s: solved map wrap partial", Name)
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continue
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}
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case *EqualityWrapStructInvariant:
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if _, exists := structPartials[eq.Expr1]; !exists {
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structPartials[eq.Expr1] = make(map[interfaces.Expr]*types.Type)
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}
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if typ, exists := solved[eq.Expr1]; exists {
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// wow, now known, so tell the partials!
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for i, name := range eq.Expr2Ord {
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expr := eq.Expr2Map[name] // assume key exists
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structPartials[eq.Expr1][expr] = typ.Map[typ.Ord[i]] // assume key exists
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}
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}
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// can we add to partials ?
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for name, y := range eq.Expr2Map {
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typ, exists := solved[y]
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if !exists {
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continue
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}
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t, exists := structPartials[eq.Expr1][y]
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if !exists {
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structPartials[eq.Expr1][y] = typ // learn!
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continue
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}
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with partial struct field: %s", name)
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}
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}
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// can we solve anything?
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var ready = true // assume ready
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typ := &types.Type{
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Kind: types.KindStruct,
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}
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typ.Map = make(map[string]*types.Type)
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for name, y := range eq.Expr2Map {
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t, exists := structPartials[eq.Expr1][y]
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if !exists {
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ready = false // nope!
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break
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}
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typ.Map[name] = t // build up typ
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}
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if ready {
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typ.Ord = eq.Expr2Ord // known order
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if t, exists := solved[eq.Expr1]; exists {
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with struct")
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}
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}
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// sub checks
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for name, y := range eq.Expr2Map {
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if t, exists := solved[y]; exists {
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if err := t.Cmp(typ.Map[name]); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with struct field: %s", name)
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}
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}
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}
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solved[eq.Expr1] = typ // yay, we learned something!
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// we should add the other expr's in too...
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for name, y := range eq.Expr2Map {
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solved[y] = typ.Map[name] // yay, we learned something!
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}
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used = append(used, i) // mark equality as used up
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logf("%s: solved struct wrap partial", Name)
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continue
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}
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case *EqualityWrapFuncInvariant:
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if _, exists := funcPartials[eq.Expr1]; !exists {
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funcPartials[eq.Expr1] = make(map[interfaces.Expr]*types.Type)
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}
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if typ, exists := solved[eq.Expr1]; exists {
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// wow, now known, so tell the partials!
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for i, name := range eq.Expr2Ord {
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expr := eq.Expr2Map[name] // assume key exists
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funcPartials[eq.Expr1][expr] = typ.Map[typ.Ord[i]] // assume key exists
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}
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funcPartials[eq.Expr1][eq.Expr2Out] = typ.Out
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}
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// can we add to partials ?
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for name, y := range eq.Expr2Map {
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typ, exists := solved[y]
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if !exists {
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continue
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}
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t, exists := funcPartials[eq.Expr1][y]
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if !exists {
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funcPartials[eq.Expr1][y] = typ // learn!
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continue
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}
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with partial func arg: %s", name)
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}
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}
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for _, y := range []interfaces.Expr{eq.Expr2Out} {
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typ, exists := solved[y]
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if !exists {
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continue
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}
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t, exists := funcPartials[eq.Expr1][y]
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if !exists {
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funcPartials[eq.Expr1][y] = typ // learn!
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continue
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}
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with partial func arg")
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}
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}
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// can we solve anything?
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var ready = true // assume ready
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typ := &types.Type{
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Kind: types.KindFunc,
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}
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typ.Map = make(map[string]*types.Type)
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for name, y := range eq.Expr2Map {
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t, exists := funcPartials[eq.Expr1][y]
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if !exists {
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ready = false // nope!
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break
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}
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typ.Map[name] = t // build up typ
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}
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outTyp, exists := funcPartials[eq.Expr1][eq.Expr2Out]
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if !exists {
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ready = false // nope!
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} else {
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typ.Out = outTyp // build up typ
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}
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if ready {
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typ.Ord = eq.Expr2Ord // known order
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if t, exists := solved[eq.Expr1]; exists {
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if err := t.Cmp(typ); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with func")
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}
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}
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// sub checks
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for name, y := range eq.Expr2Map {
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if t, exists := solved[y]; exists {
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if err := t.Cmp(typ.Map[name]); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with func arg: %s", name)
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}
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}
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}
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if t, exists := solved[eq.Expr2Out]; exists {
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if err := t.Cmp(typ.Out); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with func out")
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}
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}
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solved[eq.Expr1] = typ // yay, we learned something!
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// we should add the other expr's in too...
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for name, y := range eq.Expr2Map {
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solved[y] = typ.Map[name] // yay, we learned something!
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}
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solved[eq.Expr2Out] = typ.Out // yay, we learned something!
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used = append(used, i) // mark equality as used up
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logf("%s: solved func wrap partial", Name)
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continue
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}
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// regular matching
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case *EqualityInvariant:
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typ1, exists1 := solved[eq.Expr1]
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typ2, exists2 := solved[eq.Expr2]
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if !exists1 && !exists2 { // neither equality connects
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// can't learn more from this equality yet
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// nothing is known about either side of it
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continue
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}
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if exists1 && exists2 { // both equalities already connect
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// both sides are already known-- are they the same?
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if err := typ1.Cmp(typ2); err != nil {
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return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with equality")
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}
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used = append(used, i) // mark equality as used up
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logf("%s: duplicate regular equality", Name)
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continue
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}
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if exists1 && !exists2 { // first equality already connects
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solved[eq.Expr2] = typ1 // yay, we learned something!
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used = append(used, i) // mark equality as used up
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logf("%s: solved regular equality", Name)
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continue
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}
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if exists2 && !exists1 { // second equality already connects
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solved[eq.Expr1] = typ2 // yay, we learned something!
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used = append(used, i) // mark equality as used up
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logf("%s: solved regular equality", Name)
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continue
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}
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panic("reached unexpected code")
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// wtf matching
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case *AnyInvariant:
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// this basically ensures that the expr gets solved
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if _, exists := solved[eq.Expr]; exists {
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used = append(used, i) // mark equality as used up
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logf("%s: solved `any` equality", Name)
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}
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continue
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default:
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return nil, fmt.Errorf("unknown invariant type: %T", x)
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}
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} // end inner for loop
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if len(used) == 0 {
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// looks like we're now ambiguous, but if we have any
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// exclusives, recurse into each possibility to see if
|
|
// one of them can help solve this! first one wins. add
|
|
// in the exclusive to the current set of equalities!
|
|
|
|
// what have we learned for sure so far?
|
|
partialSolutions := []interfaces.Invariant{}
|
|
logf("%s: %d solved, %d unsolved, and %d exclusives left", Name, len(solved), len(equalities), len(exclusives))
|
|
if len(exclusives) > 0 {
|
|
// FIXME: can we do this loop in a deterministic, sorted way?
|
|
for expr, typ := range solved {
|
|
invar := &EqualsInvariant{
|
|
Expr: expr,
|
|
Type: typ,
|
|
}
|
|
partialSolutions = append(partialSolutions, invar)
|
|
logf("%s: solved: %+v", Name, invar)
|
|
}
|
|
|
|
// also include anything that hasn't been solved yet
|
|
for _, x := range equalities {
|
|
partialSolutions = append(partialSolutions, x)
|
|
logf("%s: unsolved: %+v", Name, x)
|
|
}
|
|
}
|
|
|
|
// let's try each combination, one at a time...
|
|
for i, ex := range exclusivesProduct(exclusives) { // [][]interfaces.Invariant
|
|
logf("%s: exclusive(%d):\n%+v", Name, i, ex)
|
|
// we could waste a lot of cpu, and start from
|
|
// the beginning, but instead we could use the
|
|
// list of known solutions found and continue!
|
|
// TODO: make sure none of these edit partialSolutions
|
|
recursiveInvariants := []interfaces.Invariant{}
|
|
recursiveInvariants = append(recursiveInvariants, partialSolutions...)
|
|
recursiveInvariants = append(recursiveInvariants, ex...)
|
|
logf("%s: recursing...", Name)
|
|
solution, err := SimpleInvariantSolver(recursiveInvariants, logf)
|
|
if err != nil {
|
|
logf("%s: recursive solution failed: %+v", Name, err)
|
|
continue // no solution found here...
|
|
}
|
|
// solution found!
|
|
logf("%s: recursive solution found!", Name)
|
|
return solution, nil
|
|
}
|
|
|
|
// TODO: print ambiguity
|
|
return nil, fmt.Errorf("can't unify, no equalities were consumed, we're ambiguous")
|
|
}
|
|
// delete used equalities, in reverse order to preserve indexing!
|
|
for i := len(used) - 1; i >= 0; i-- {
|
|
ix := used[i] // delete index that was marked as used!
|
|
equalities = append(equalities[:ix], equalities[ix+1:]...)
|
|
}
|
|
} // end giant for loop
|
|
|
|
// build final solution
|
|
solutions := []*EqualsInvariant{}
|
|
// FIXME: can we do this loop in a deterministic, sorted way?
|
|
for expr, typ := range solved {
|
|
invar := &EqualsInvariant{
|
|
Expr: expr,
|
|
Type: typ,
|
|
}
|
|
solutions = append(solutions, invar)
|
|
}
|
|
return &InvariantSolution{
|
|
Solutions: solutions,
|
|
}, nil
|
|
}
|