From 95bbbc63cb56b7f6954ae94bf108bc4f726020d6 Mon Sep 17 00:00:00 2001
From: Jeroen Engels <jfm.engels@gmail.com>
Date: Sun, 23 Jun 2019 18:08:00 +0200
Subject: [PATCH] Start a new Rule implementation

---
 src/Lint/Rule2.elm | 212 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 212 insertions(+)
 create mode 100644 src/Lint/Rule2.elm

diff --git a/src/Lint/Rule2.elm b/src/Lint/Rule2.elm
new file mode 100644
index 00000000..c998ac67
--- /dev/null
+++ b/src/Lint/Rule2.elm
@@ -0,0 +1,212 @@
+module Lint.Rule2 exposing
+    ( Rule2
+    , newRuleSchema
+    , withSimpleModuleDefinitionVisitor, withSimpleImportVisitor, withSimpleExpressionVisitor, withSimpleDeclarationVisitor
+    , withModuleDefinitionVisitor, withImportVisitor, withExpressionVisitor, withDeclarationVisitor, withFinalEvaluation
+    , evaluateDeclaration, evaluateExpression, evaluateImport, evaluateModuleDefinition, finalEvaluation, initialContext
+    , Visitor2
+    )
+
+{-| This module contains functions that are used for writing rules.
+
+
+# Definition
+
+@docs Rule2
+
+
+# Writing rules
+
+@docs newRuleSchema
+@docs withSimpleModuleDefinitionVisitor, withSimpleImportVisitor, withSimpleExpressionVisitor, withSimpleDeclarationVisitor
+@docs withModuleDefinitionVisitor, withImportVisitor, withExpressionVisitor, withDeclarationVisitor, withFinalEvaluation
+
+
+# ACCESS
+
+@docs evaluateDeclaration, evaluateExpression, evaluateImport, evaluateModuleDefinition, finalEvaluation, initialContext
+
+
+# Internal types
+
+@docs Visitor
+
+-}
+
+import Elm.Syntax.Declaration exposing (Declaration)
+import Elm.Syntax.Expression exposing (Expression)
+import Elm.Syntax.File exposing (File)
+import Elm.Syntax.Import exposing (Import)
+import Elm.Syntax.Module exposing (Module)
+import Elm.Syntax.Node exposing (Node)
+import Elm.Syntax.TypeAnnotation exposing (TypeAnnotation)
+import Lint.Direction as Direction exposing (Direction)
+import Lint.Error exposing (Error)
+
+
+{-| Represents a `rule` that will be enforced.
+
+        import Lint.Rule as Rule
+
+        rule : Rule
+        rule =
+            Rule.newRuleSchema "NoDebug"
+                |> Rule.withExpressionVisitor expressionVisitor
+                |> Rule.fromSchema
+
+-}
+type Rule2 context
+    = Rule2
+        { name : String
+        , initialContext : context
+        , moduleDefinitionVisitor : context -> Node Module -> ( List Error, context )
+        , importVisitor : context -> Node Import -> ( List Error, context )
+        , expressionVisitor : context -> Direction -> Node Expression -> ( List Error, context )
+        , declarationVisitor : context -> Direction -> Node Declaration -> ( List Error, context )
+        , finalEvaluationFn : context -> List Error
+        }
+
+
+{-| Creates a new schema for a rule. Will require calling `fromSchema` to create a usable `Rule`.
+-}
+newRuleSchema : String -> Rule2 ()
+newRuleSchema name =
+    Rule2
+        { name = name
+        , initialContext = ()
+        , moduleDefinitionVisitor = \context node -> ( [], context )
+        , importVisitor = \context node -> ( [], context )
+        , expressionVisitor = \context direction node -> ( [], context )
+        , declarationVisitor = \context direction node -> ( [], context )
+        , finalEvaluationFn = \context -> []
+        }
+
+
+
+-- TODO
+-- fromSchema : Rule2 () -> ...
+
+
+withInitialContext : context -> Rule2 () -> Rule2 context
+withInitialContext initialContext_ (Rule2 rule) =
+    Rule2
+        { name = rule.name
+        , initialContext = initialContext_
+        , moduleDefinitionVisitor = \context node -> ( [], context )
+        , importVisitor = \context node -> ( [], context )
+        , expressionVisitor = \context direction node -> ( [], context )
+        , declarationVisitor = \context direction node -> ( [], context )
+        , finalEvaluationFn = \context -> []
+        }
+
+
+withModuleDefinitionVisitor : (context -> Node Module -> ( List Error, context )) -> Rule2 context -> Rule2 context
+withModuleDefinitionVisitor visitor (Rule2 rule) =
+    Rule2 { rule | moduleDefinitionVisitor = visitor }
+
+
+withImportVisitor : (context -> Node Import -> ( List Error, context )) -> Rule2 context -> Rule2 context
+withImportVisitor visitor (Rule2 rule) =
+    Rule2 { rule | importVisitor = visitor }
+
+
+withExpressionVisitor : (context -> Direction -> Node Expression -> ( List Error, context )) -> Rule2 context -> Rule2 context
+withExpressionVisitor visitor (Rule2 rule) =
+    Rule2 { rule | expressionVisitor = visitor }
+
+
+withDeclarationVisitor : (context -> Direction -> Node Declaration -> ( List Error, context )) -> Rule2 context -> Rule2 context
+withDeclarationVisitor visitor (Rule2 rule) =
+    Rule2 { rule | declarationVisitor = visitor }
+
+
+withFinalEvaluation : (context -> List Error) -> Rule2 context -> Rule2 context
+withFinalEvaluation visitor (Rule2 rule) =
+    Rule2 { rule | finalEvaluationFn = visitor }
+
+
+
+-- RULES WITHOUT ANALYSIS
+
+
+withSimpleModuleDefinitionVisitor : (Node Module -> List Error) -> Rule2 context -> Rule2 context
+withSimpleModuleDefinitionVisitor visitor (Rule2 rule) =
+    Rule2 { rule | moduleDefinitionVisitor = \context node -> ( visitor node, context ) }
+
+
+withSimpleImportVisitor : (Node Import -> List Error) -> Rule2 context -> Rule2 context
+withSimpleImportVisitor visitor (Rule2 rule) =
+    Rule2 { rule | importVisitor = \context node -> ( visitor node, context ) }
+
+
+withSimpleExpressionVisitor : (Node Expression -> List Error) -> Rule2 context -> Rule2 context
+withSimpleExpressionVisitor visitor (Rule2 rule) =
+    Rule2
+        { rule
+            | expressionVisitor =
+                \context direction node ->
+                    case direction of
+                        Direction.Enter ->
+                            ( visitor node, context )
+
+                        Direction.Exit ->
+                            ( [], context )
+        }
+
+
+withSimpleDeclarationVisitor : (Node Declaration -> List Error) -> Rule2 context -> Rule2 context
+withSimpleDeclarationVisitor visitor (Rule2 rule) =
+    Rule2
+        { rule
+            | declarationVisitor =
+                \context direction node ->
+                    case direction of
+                        Direction.Enter ->
+                            ( visitor node, context )
+
+                        Direction.Exit ->
+                            ( [], context )
+        }
+
+
+
+-- RULE CONSTRUCTOR AND BUILDERS
+-- RULES WITH ANALYSES
+-- ACCESS
+
+
+initialContext : Rule2 context -> context
+initialContext (Rule2 rule) =
+    rule.initialContext
+
+
+evaluateModuleDefinition : Rule2 context -> context -> Node Module -> ( List Error, context )
+evaluateModuleDefinition (Rule2 rule) =
+    rule.moduleDefinitionVisitor
+
+
+evaluateImport : Rule2 context -> context -> Node Import -> ( List Error, context )
+evaluateImport (Rule2 rule) =
+    rule.importVisitor
+
+
+evaluateExpression : Rule2 context -> context -> Direction -> Node Expression -> ( List Error, context )
+evaluateExpression (Rule2 rule) =
+    rule.expressionVisitor
+
+
+evaluateDeclaration : Rule2 context -> context -> Direction -> Node Declaration -> ( List Error, context )
+evaluateDeclaration (Rule2 rule) =
+    rule.declarationVisitor
+
+
+finalEvaluation : Rule2 context -> context -> List Error
+finalEvaluation (Rule2 rule) =
+    rule.finalEvaluationFn
+
+
+{-| Shorthand for a function that takes a rule's implementation, a context and returns ( List Lint.Error.Error, context ).
+A Visitor represents a node and calls the appropriate function for the given node type.
+-}
+type alias Visitor2 context =
+    Rule2 context -> context -> ( List Error, context )