Add variables

.gitignore

@@ -1 +1,2 @@
 node_modules
+.tool-versions

README.md

@@ -18,7 +18,7 @@ Snippets files are stored in a package's `snippets/` folder and also loaded from
 
 The outermost keys are the selectors where these snippets should be active, prefixed with a period (`.`) (details below).
 
-The next level of keys are the snippet names.
+The next level of keys are the snippet names. Because this is object notation, each snippet must have a different name.
 
 Under each snippet name is a `body` to insert when the snippet is triggered.
 
@@ -32,24 +32,26 @@ console.log("crash");
 
 The string `"crash"` would be initially selected and pressing tab again would place the cursor after the `;`
 
-A snippet must define **at least one** of the following keys:
+A snippet specifies how it can be triggered. Thus it must provide **at least one** of the following keys:
 
 ### The ‘prefix’ key
 
-If a `prefix` is defined, it specifies a string that can trigger the snippet: type the string in the editor and press <kbd>Tab</kbd>. In this example, typing `log` (as its own word) and then pressing <kbd>Tab</kbd> would replace `log` with the string `console.log("crash")` as described above.
+If a `prefix` is defined, it specifies a string that can trigger the snippet. In the above example, typing `log` (as its own word) and then pressing <kbd>Tab</kbd> would replace `log` with the string `console.log("crash")` as described above.
 
 Prefix completions can be suggested if partially typed thanks to the `autocomplete-snippets` package.
 
 ### The ‘command’ key
 
 If a `command` is defined, it specifies a command name that can trigger the snippet. That command can be invoked from the command palette or mapped to a keyboard shortcut via your `keymap.cson`.
 
-If you defined the `console.log` snippet described above in your own `snippets.cson`, it would be available in the command palette as “Snippets: Insert Console Log”, or could be referenced in a keymap file as `snippets:insert-console-log`.
+If a package called `some-package` had defined that snippet, it would be available in the keymap as `some-package:insert-console-log`, or in the command palette as **Some Package: Insert Console Log**.
 
-If a package called `some-package` had defined that snippet, it would be available in the keymap as `some-package:insert-console-log`, or in the command palette as “Some Package: Insert Console Log”.
+If you defined the `console.log` snippet described above in your own `snippets.cson`, it could be referenced in a keymap file as `snippets:insert-console-log`, or in the command palette as **Snippets: Insert Console Log**.
 
 Invoking the command would insert the snippet at the cursor, replacing any text that may be selected.
 
+Snippet command names must be unique. They can’t conflict with each other, nor can they conflict with any other commands that have been defined. If there is such a conflict, you’ll see an error notification describing the problem.
+
 ### Optional parameters
 
 These parameters are meant to provide extra information about your snippet to [autocomplete-plus](https://github.com/atom/autocomplete-plus/wiki/Provider-API).
@@ -74,24 +76,76 @@ Example:
 
 ### Determining the correct scope for a snippet
 
-The outmost key of a snippet is the "scope" that you want the descendent snippets to be available in. The key should be prefixed with a period (`text.html.basic` => `.text.html.basic`). You can find out the correct scope by opening the Settings (<kbd>cmd-,</kbd> on macOS) and selecting the corresponding *Language [xxx]* package, e.g. for *Language Html*:
+The outmost key of a snippet is the “scope” that you want the descendent snippets to be available in. The key should be prefixed with a period (`text.html.basic` → `.text.html.basic`). You can find out the correct scope by opening the Settings (<kbd>cmd-,</kbd> on macOS) and selecting the corresponding *Language [xxx]* package. For example, here’s the settings page for `language-html`:
 
 ![Screenshot of Language Html settings](https://cloud.githubusercontent.com/assets/1038121/5137632/126beb66-70f2-11e4-839b-bc7e84103f67.png)
 
-If it's difficult to determine the package handling the file type in question (for example, for `.md`-documents), you can also proceed as following. Put your cursor in a file in which you want the snippet to be available, open the [Command Palette](https://github.com/pulsar-edit/command-palette)
-(<kbd>cmd-shift-p</kbd>), and run the `Editor: Log Cursor Scope` command. This will trigger a notification which will contain a list of scopes. The first scope that's listed is the scope for that language. Here are some examples: `source.coffee`, `text.plain`, `text.html.basic`.
+If it's difficult to determine the package handling the file type in question (for example, for `.md`-documents), you can use another approach:
+
+1. Put your cursor in a file in which you want the snippet to be available.
+2. Open the [Command Palette](https://github.com/pulsar-edit/command-palette)
+(<kbd>cmd-shift-p</kbd> or <kbd>ctrl-shift-p</kbd>).
+3. Run the `Editor: Log Cursor Scope` command.
+
+This will trigger a notification which will contain a list of scopes. The first scope that's listed is the scope for that language. Here are some examples: `source.coffee`, `text.plain`, `text.html.basic`.
+
+## Snippet syntax
+
+This package supports a subset of the features of TextMate snippets, [documented here](http://manual.macromates.com/en/snippets), as well as most features described in the [LSP specification][lsp] and [supported by VSCode][vscode].
+
+The following features from TextMate snippets are not yet supported:
+
+* Interpolated shell code can’t reliably be supported cross-platform, and is probably a bad idea anyway. No other editors that support snippets have adopted this feature, and Pulsar won’t either.
+
+The following features from VSCode snippets are not yet supported:
+
+* “Choice” syntax like `${1|one,two,three|}` requires that the autocomplete engine pop up a menu to offer the user a choice between the available placeholder options. This may be supported in the future, but right now Pulsar effectively converts this to `${1:one}`, treating the first choice as a conventional placeholder.
+
+### Variables
+
+Pulsar snippets support all of the variables mentioned in the [LSP specification][lsp], plus many of the variables [supported by VSCode][vscode].
+
+Variables can be referenced with `$`, either without braces (`$CLIPBOARD`) or with braces (`${CLIPBOARD}`). Variables can also have fallback values (`${CLIPBOARD:http://example.com}`), simple flag-based transformations (`${CLIPBOARD:/upcase}`), or `sed`-style transformations `${CLIPBOARD/ /_/g}`.
 
-### Snippet syntax
+One of the most useful is `TM_SELECTED_TEXT`, which represents whatever text was selected when the snippet was invoked. (Naturally, this can only happen when a snippet is invoked via command or key shortcut, rather than by typing in a <kbd>Tab</kbd> trigger.)
 
-This package supports a subset of the features of TextMate snippets, [documented here](http://manual.macromates.com/en/snippets#transformations).
+Others that can be useful:
 
-The following features are not yet supported:
+* `TM_FILENAME`: The name of the current file (`foo.rb`).
+* `TM_FILENAME_BASE`: The name of the current file, but without its extension (`foo`).
+* `TM_FILEPATH`: The entire path on disk to the current file.
+* `TM_CURRENT_LINE`: The entire current line that the cursor is sitting on.
+* `TM_CURRENT_WORD`: The entire word that the cursor is within or adjacent to, as interpreted by `cursor.getCurrentWordBufferRange`.
+* `CLIPBOARD`: The current contents of the clipboard.
+* `CURRENT_YEAR`, `CURRENT_MONTH`, et cetera: referneces to the current date and time in various formats.
 
-* Variables
-* Interpolated shell code
-* Conditional insertions in transformations
+Any variable that has no value — for instance, `TM_FILENAME` on an untitled document — will resolve to an empty string.
 
-### Multi-line Snippet Body
+#### Variable transformation flags
+
+Pulsar supports the three flags defined in the [LSP snippets specification][lsp] and two other flags that are [implemented in VSCode][vscode]:
+
+* `/upcase` (`foo` → `FOO`)
+* `/downcase` (`BAR` → `bar`)
+* `/capitalize` (`lorem ipsum dolor` → `Lorem ipsum dolor`)
+* `/camelcase` (`foo bar` → `fooBar`, `lorem-ipsum.dolor` → `loremIpsumDolor`)
+* `/pascalcase` (`foo bar` → `FooBar`, `lorem-ipsum.dolor` → `LoremIpsumDolor`)
+
+#### Variable caveats
+
+* `WORKSPACE_NAME`, `WORKSPACE_FOLDER`, and `RELATIVE_PATH` all rely on the presence of a root project folder, but a Pulsar project can technically have multiple root folders. While this is rare, it is handled by `snippets` as follows: whichever project path is an ancestor of the currently active file is treated as the project root — or the first one found if multiple roots are ancestors.
+* `WORKSPACE_NAME` in VSCode refers to “the name of the opened workspace or folder.” In the former case, this appears to mean bundled projects with a `.code-workspace` file extension — which have no Pulsar equivalent. Instead, `WORKSPACE_NAME` will always refer to the last path component of your project’s root directory as defined above.
+
+#### Variables that are not yet supported
+
+Of the variables supported by VSCode, Pulsar does not yet support:
+
+* `UUID`
+* `BLOCK_COMMENT_START`
+* `BLOCK_COMMENT_END`
+* `LINE_COMMENT`
+
+## Multi-line Snippet Body
 
 You can also use multi-line syntax using `"""` for larger templates:
 
@@ -110,7 +164,7 @@ You can also use multi-line syntax using `"""` for larger templates:
     """
 ```
 
-### Escaping Characters
+## Escaping Characters
 
 Including a literal closing brace inside the text provided by a snippet's tab stop will close that tab stop early. To prevent that, escape the brace with two backslashes, like so:
 
@@ -127,6 +181,12 @@ Including a literal closing brace inside the text provided by a snippet's tab st
       """
 ```
 
-### Multiple snippets for the same scope
+Likewise, if your snippet includes literal references to `$` or `{`, you may have to escape those with two backslashes as well, depending on the context.
+
+## Multiple snippets for the same scope
+
+Snippets for the same scope must be placed within the same key. See [this section of the Pulsar Flight Manual](https://pulsar-edit.dev/docs/launch-manual/sections/using-pulsar/#configuring-with-cson) for more information.
+
 
-Snippets for the same scope must be placed within the same key. See [this section of the Atom Flight Manual](https://pulsar-edit.dev/docs/atom-archive/using-atom/#configuring-with-cson) for more information.
+[lsp]: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#variables
+[vscode]: https://code.visualstudio.com/docs/editor/userdefinedsnippets#_variables

lib/insertion.js

@@ -1,94 +1,30 @@
-const ESCAPES = {
-  u: (flags) => {
-    flags.lowercaseNext = false
-    flags.uppercaseNext = true
-  },
-  l: (flags) => {
-    flags.uppercaseNext = false
-    flags.lowercaseNext = true
-  },
-  U: (flags) => {
-    flags.lowercaseAll = false
-    flags.uppercaseAll = true
-  },
-  L: (flags) => {
-    flags.uppercaseAll = false
-    flags.lowercaseAll = true
-  },
-  E: (flags) => {
-    flags.uppercaseAll = false
-    flags.lowercaseAll = false
-  },
-  r: (flags, result) => {
-    result.push('\\r')
-  },
-  n: (flags, result) => {
-    result.push('\\n')
-  },
-  $: (flags, result) => {
-    result.push('$')
-  }
-}
-
-function transformText (str, flags) {
-  if (flags.uppercaseAll) {
-    return str.toUpperCase()
-  } else if (flags.lowercaseAll) {
-    return str.toLowerCase()
-  } else if (flags.uppercaseNext) {
-    flags.uppercaseNext = false
-    return str.replace(/^./, s => s.toUpperCase())
-  } else if (flags.lowercaseNext) {
-    return str.replace(/^./, s => s.toLowerCase())
-  }
-  return str
-}
+const Replacer = require('./replacer')
 
 class Insertion {
-  constructor ({ range, substitution, references }) {
+  constructor ({range, substitution, references}) {
     this.range = range
     this.substitution = substitution
     this.references = references
     if (substitution) {
       if (substitution.replace === undefined) {
         substitution.replace = ''
       }
-      this.replacer = this.makeReplacer(substitution.replace)
+      this.replacer = new Replacer(substitution.replace)
     }
   }
 
   isTransformation () {
     return !!this.substitution
   }
 
-  makeReplacer (replace) {
-    return function replacer (...match) {
-      let flags = {
-        uppercaseAll: false,
-        lowercaseAll: false,
-        uppercaseNext: false,
-        lowercaseNext: false
-      }
-      replace = [...replace]
-      let result = []
-      replace.forEach(token => {
-        if (typeof token === 'string') {
-          result.push(transformText(token, flags))
-        } else if (token.escape) {
-          ESCAPES[token.escape](flags, result)
-        } else if (token.backreference) {
-          let transformed = transformText(match[token.backreference], flags)
-          result.push(transformed)
-        }
-      })
-      return result.join('')
-    }
-  }
-
   transform (input) {
-    let { substitution } = this
+    let {substitution} = this
     if (!substitution) { return input }
-    return input.replace(substitution.find, this.replacer)
+    this.replacer.resetFlags()
+    return input.replace(substitution.find, (...args) => {
+      let result = this.replacer.replace(...args)
+      return result
+    })
   }
 }
 

lib/replacer.js

@@ -0,0 +1,100 @@
+const ESCAPES = {
+  u: (flags) => {
+    flags.lowercaseNext = false
+    flags.uppercaseNext = true
+  },
+  l: (flags) => {
+    flags.uppercaseNext = false
+    flags.lowercaseNext = true
+  },
+  U: (flags) => {
+    flags.lowercaseAll = false
+    flags.uppercaseAll = true
+  },
+  L: (flags) => {
+    flags.uppercaseAll = false
+    flags.lowercaseAll = true
+  },
+  E: (flags) => {
+    flags.uppercaseAll = false
+    flags.lowercaseAll = false
+  },
+  r: (flags, result) => {
+    result.push('\\r')
+  },
+  n: (flags, result) => {
+    result.push('\\n')
+  },
+  $: (flags, result) => {
+    result.push('$')
+  }
+}
+
+function transformTextWithFlags (str, flags) {
+  if (flags.uppercaseAll) {
+    return str.toUpperCase()
+  } else if (flags.lowercaseAll) {
+    return str.toLowerCase()
+  } else if (flags.uppercaseNext) {
+    flags.uppercaseNext = false
+    return str.replace(/^./, s => s.toUpperCase())
+  } else if (flags.lowercaseNext) {
+    return str.replace(/^./, s => s.toLowerCase())
+  }
+  return str
+}
+
+
+// `Replacer` handles shared substitution semantics for tabstop and variable
+// transformations.
+class Replacer {
+  constructor (tokens) {
+    this.tokens = [...tokens]
+    this.resetFlags()
+  }
+
+  resetFlags () {
+    this.flags = {
+      uppercaseAll: false,
+      lowercaseAll: false,
+      uppercaseNext: false,
+      lowercaseNext: false
+    }
+  }
+
+  replace (...match) {
+    let result = []
+
+    function handleToken (token) {
+      if (typeof token === 'string') {
+        result.push(transformTextWithFlags(token, this.flags))
+      } else if (token.escape) {
+        ESCAPES[token.escape](this.flags, result)
+      } else if (token.backreference) {
+        let {iftext, elsetext} = token
+        if (iftext != null && elsetext != null) {
+          // If-else syntax makes choices based on the presence or absence of a
+          // capture group backreference.
+          let m = match[token.backreference]
+          let tokenToHandle = m ? iftext : elsetext
+          if (Array.isArray(tokenToHandle)) {
+            result.push(...tokenToHandle.map(handleToken.bind(this)))
+          } else {
+            result.push(handleToken.call(this, tokenToHandle))
+          }
+        } else {
+          let transformed = transformTextWithFlags(
+            match[token.backreference],
+            this.flags
+          )
+          result.push(transformed)
+        }
+      }
+    }
+
+    this.tokens.forEach(handleToken.bind(this))
+    return result.join('')
+  }
+}
+
+module.exports = Replacer