lang: Split lang package out into many subpackages

This is a giant refactor to split the giant lang package into many
subpackages. The most difficult piece was figuring out how to extract
the extra ast structs into their own package, because they needed to
call two functions which also needed to import the ast.

The solution was to separate out those functions into their own
packages, and to pass them into the ast at the root when they're needed,
and to let the relevant ast portions call a handle.

This isn't terribly ugly because we already had a giant data struct
woven through the ast.

The bad part is rebasing any WIP work on top of this.

lang/ast/scope_test.go

@@ -0,0 +1,179 @@
+// Mgmt
+// Copyright (C) 2013-2021+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// +build !root
+
+package ast
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"github.com/purpleidea/mgmt/lang/interfaces"
+	"github.com/purpleidea/mgmt/util"
+)
+
+func TestScopeIndexesPush0(t *testing.T) {
+	type test struct { // an individual test
+		name     string
+		indexes  map[int][]interfaces.Expr
+		pushed   []interfaces.Expr
+		expected map[int][]interfaces.Expr
+	}
+	testCases := []test{}
+
+	//{
+	//	testCases = append(testCases, test{
+	//		name: "empty",
+	//		pushed: nil, // TODO: undefined, but should we do it?
+	//		expected: map[int][]interfaces.Expr{
+	//			0: {}, // empty list ?
+	//		},
+	//	})
+	//}
+	{
+		testCases = append(testCases, test{
+			name:   "empty list",
+			pushed: []interfaces.Expr{}, // empty list
+			expected: map[int][]interfaces.Expr{
+				0: {}, // empty list
+			},
+		})
+	}
+	{
+		b1 := &ExprBool{}
+		b2 := &ExprBool{}
+		b3 := &ExprBool{}
+		b4 := &ExprBool{}
+		b5 := &ExprBool{}
+		b6 := &ExprBool{}
+		b7 := &ExprBool{}
+		b8 := &ExprBool{}
+		testCases = append(testCases, test{
+			name: "simple push",
+			indexes: map[int][]interfaces.Expr{
+				0: {
+					b1, b2, b3,
+				},
+				1: {
+					b4,
+				},
+				2: {
+					b5, b6,
+				},
+			},
+			pushed: []interfaces.Expr{
+				b7, b8,
+			},
+			expected: map[int][]interfaces.Expr{
+				0: {
+					b7, b8,
+				},
+				1: {
+					b1, b2, b3,
+				},
+				2: {
+					b4,
+				},
+				3: {
+					b5, b6,
+				},
+			},
+		})
+	}
+	{
+		b1 := &ExprBool{}
+		b2 := &ExprBool{}
+		b3 := &ExprBool{}
+		b4 := &ExprBool{}
+		b5 := &ExprBool{}
+		b6 := &ExprBool{}
+		b7 := &ExprBool{}
+		b8 := &ExprBool{}
+		testCases = append(testCases, test{
+			name: "push with gaps",
+			indexes: map[int][]interfaces.Expr{
+				0: {
+					b1, b2, b3,
+				},
+				// there is a gap here
+				2: {
+					b4,
+				},
+				3: {
+					b5, b6,
+				},
+			},
+			pushed: []interfaces.Expr{
+				b7, b8,
+			},
+			expected: map[int][]interfaces.Expr{
+				0: {
+					b7, b8,
+				},
+				// the gap remains
+				1: {
+					b1, b2, b3,
+				},
+				3: {
+					b4,
+				},
+				4: {
+					b5, b6,
+				},
+			},
+		})
+	}
+	names := []string{}
+	for index, tc := range testCases { // run all the tests
+		if tc.name == "" {
+			t.Errorf("test #%d: not named", index)
+			continue
+		}
+		if util.StrInList(tc.name, names) {
+			t.Errorf("test #%d: duplicate sub test name of: %s", index, tc.name)
+			continue
+		}
+		names = append(names, tc.name)
+
+		//if index != 3 { // hack to run a subset (useful for debugging)
+		//if (index != 20 && index != 21) {
+		//if tc.name != "nil" {
+		//	continue
+		//}
+
+		t.Run(fmt.Sprintf("test #%d (%s)", index, tc.name), func(t *testing.T) {
+			name, indexes, pushed, expected := tc.name, tc.indexes, tc.pushed, tc.expected
+
+			t.Logf("\n\ntest #%d (%s) ----------------\n\n", index, name)
+
+			scope := &interfaces.Scope{
+				Indexes: indexes,
+			}
+			scope.PushIndexes(pushed)
+			out := scope.Indexes
+
+			if !reflect.DeepEqual(out, expected) {
+				t.Errorf("test #%d: indexes did not match expected", index)
+				t.Logf("test #%d:   actual: \n\n%+v\n", index, out)
+				t.Logf("test #%d: expected: \n\n%+v", index, expected)
+				return
+			}
+		})
+	}
+}