feat(formatting/#785): Default format provider when no extension provider (#2022)

* Formatting

* Formatting

* Add default format strategy

* Process indentation ranges

* Additional cases

* Hook up language configuration

* Remove test that no longer applies

Author: bryphe

src/Core/Indentation.re

@@ -4,6 +4,23 @@
  * Helpers for dealing with indentation level
  */
 
+open Utility;
+
+let getLeadingWhitespace = (s: string) => {
+  let rec loop = (i, spaces, tabs) =>
+    if (i >= String.length(s)) {
+      (spaces, tabs, false);
+    } else {
+      switch (s.[i]) {
+      | ' ' => loop(i + 1, spaces + 1, tabs)
+      | '\t' => loop(i + 1, spaces, tabs + 1)
+      | _ => (spaces, tabs, true)
+      };
+    };
+
+  loop(0, 0, 0);
+};
+
 let getLevel = (settings: IndentationSettings.t, text: string) => {
   let tabSize = settings.tabSize;
 
@@ -38,6 +55,22 @@ let getLevel = (settings: IndentationSettings.t, text: string) => {
   allWhitespace^ ? 0 : indentLevel^;
 };
 
+let applyLevel =
+    (~indentation: IndentationSettings.t, ~level: int, str: string) => {
+  str
+  |> StringEx.findNonWhitespace
+  |> Option.map(idx => {
+       let desiredWhitespace =
+         switch (indentation.mode) {
+         | Tabs => String.make(level, '\t')
+         | Spaces => String.make(level * indentation.size, ' ')
+         };
+
+       desiredWhitespace ++ String.sub(str, idx, String.length(str) - idx);
+     })
+  |> Option.value(~default=str);
+};
+
 let getForBuffer = (~buffer, configuration: Configuration.t) => {
   let bufferIndentation = Buffer.getIndentation(buffer);
   switch (bufferIndentation) {

src/Core/IndentationGuesser.re

@@ -8,21 +8,6 @@ module Constants = {
   let minSpaces = 2;
 };
 
-let getLeadingWhitespace = (s: string) => {
-  let rec loop = (i, spaces, tabs) =>
-    if (i >= String.length(s)) {
-      (spaces, tabs, false);
-    } else {
-      switch (s.[i]) {
-      | ' ' => loop(i + 1, spaces + 1, tabs)
-      | '\t' => loop(i + 1, spaces, tabs + 1)
-      | _ => (spaces, tabs, true)
-      };
-    };
-
-  loop(0, 0, 0);
-};
-
 type t = {
   mode: IndentationSettings.mode,
   size: int,
@@ -62,7 +47,8 @@ let guessIndentation =
     let line = getLine(i);
     let prevLine = i == 0 ? "" : getLine(i - 1);
 
-    let (spaceCount, tabCount, foundChar) = getLeadingWhitespace(line);
+    let (spaceCount, tabCount, foundChar) =
+      Indentation.getLeadingWhitespace(line);
 
     /* Only consider lines with non-whitespace */
     if (foundChar) {
@@ -75,7 +61,7 @@ let guessIndentation =
       };
 
       let (prevSpaceCount, _, prevFoundChar) =
-        getLeadingWhitespace(prevLine);
+        Indentation.getLeadingWhitespace(prevLine);
       if (prevFoundChar) {
         let diff = abs(prevSpaceCount - spaceCount);
         if (diff >= Constants.minSpaces) {

src/Core/LanguageConfiguration.re

@@ -92,6 +92,34 @@ module BracketPair = {
   let endsWithOpenPair = ({openPair, _}, str) => {
     StringEx.endsWith(~postfix=openPair, str);
   };
+
+  let isJustClosingPair = ({closePair, _}, str) => {
+    let len = String.length(str);
+
+    let rec loop = (foundPair, idx) =>
+      if (idx >= len) {
+        foundPair;
+      } else if (foundPair) {
+        false;
+             // We found the closing pair... but there's other stuff after
+      } else {
+        let c = str.[idx];
+
+        if (c == ' ' || c == '\t') {
+          loop(foundPair, idx + 1);
+        } else if (c == closePair.[0]) {
+          loop(true, idx + 1);
+        } else {
+          false;
+        };
+      };
+
+    if (String.length(closePair) == 1) {
+      loop(false, 0);
+    } else {
+      false;
+    };
+  };
 };
 
 let defaultBrackets: list(BracketPair.t) =
@@ -226,36 +254,45 @@ let toVimAutoClosingPairs = (syntaxScope: SyntaxScope.t, configuration: t) => {
   );
 };
 
-let toAutoIndent =
+let shouldIncreaseIndent =
     (
-      {increaseIndentPattern, decreaseIndentPattern, brackets, _},
       ~previousLine as str,
       ~beforePreviousLine as _,
+      {increaseIndentPattern, brackets, _},
     ) => {
-  let increase =
-    increaseIndentPattern
-    |> Option.map(regex => OnigRegExp.test(str, regex))
-    // If no indentation pattern, fall-back to bracket pair
-    |> OptionEx.or_lazy(() =>
-         Some(
-           List.exists(
-             bracket => BracketPair.endsWithOpenPair(bracket, str),
-             brackets,
-           ),
-         )
+  increaseIndentPattern
+  |> Option.map(regex => OnigRegExp.test(str, regex))
+  // If no indentation pattern, fall-back to bracket pair
+  |> OptionEx.or_lazy(() =>
+       Some(
+         List.exists(
+           bracket => BracketPair.endsWithOpenPair(bracket, str),
+           brackets,
+         ),
        )
-    |> Option.value(~default=false);
-
-  let decrease =
-    decreaseIndentPattern
-    |> Option.map(regex => OnigRegExp.test(str, regex))
-    |> Option.value(~default=false);
-
-  if (increase) {
-    Vim.AutoIndent.IncreaseIndent;
-  } else if (decrease) {
-    Vim.AutoIndent.DecreaseIndent;
-  } else {
-    Vim.AutoIndent.KeepIndent;
+     )
+  |> Option.value(~default=false);
+};
+
+let shouldDecreaseIndent = (~line, {decreaseIndentPattern, brackets, _}) => {
+  decreaseIndentPattern
+  |> Option.map(regex => OnigRegExp.test(line, regex))
+  |> OptionEx.or_lazy(() => {
+       Some(
+         List.exists(
+           bracket => BracketPair.isJustClosingPair(bracket, line),
+           brackets,
+         ),
+       )
+     })
+  |> Option.value(~default=false);
+};
+
+let toAutoIndent = (languageConfig, ~previousLine, ~beforePreviousLine) => {
+  let increase =
+    shouldIncreaseIndent(~previousLine, ~beforePreviousLine, languageConfig);
+
+  if (increase) {Vim.AutoIndent.IncreaseIndent} else {
+    Vim.AutoIndent.KeepIndent
   };
 };

src/Core/LanguageConfiguration.rei

@@ -40,6 +40,11 @@ type t = {
 
 let default: t;
 
+let shouldIncreaseIndent:
+  (~previousLine: string, ~beforePreviousLine: option(string), t) => bool;
+
+let shouldDecreaseIndent: (~line: string, t) => bool;
+
 let decode: Json.decoder(t);
 
 let toVimAutoClosingPairs: (SyntaxScope.t, t) => Vim.AutoClosingPairs.t;

src/Core/Utility/StringEx.re

@@ -112,19 +112,29 @@ let trimRight = str => {
   aux(length - 1);
 };
 
-let indentation = str => {
-  let rec loop = i =>
-    if (i >= String.length(str)) {
-      i;
-    } else if (isSpace(str.[i])) {
-      loop(i + 1);
+let findNonWhitespace = str => {
+  let len = String.length(str);
+  let rec loop = idx =>
+    if (idx >= len) {
+      None;
     } else {
-      i;
+      let char = str.[idx];
+      if (char != '\t' && char != ' ') {
+        Some(idx);
+      } else {
+        loop(idx + 1);
+      };
     };
-
   loop(0);
 };
 
+let isOnlyWhitespace = str => {
+  switch (findNonWhitespace(str)) {
+  | None => true
+  | Some(_) => false
+  };
+};
+
 let extractSnippet = (~maxLength, ~charStart, ~charEnd, text) => {
   let originalLength = String.length(text);