Implement snippet support in ark (#183)

* Implement snippet support in ark

* Switch to `Option`, include `documentation`

crates/ark/resources/snippets/r.code-snippets

@@ -0,0 +1,181 @@
+{
+	"lib": {
+        "prefix": "lib",
+        "body": "library(${1:package})",
+		"description": "Attach an R package"
+	},
+	"src": {
+        "prefix": "src",
+        "body": "source(\"${1:file.R}\")",
+		"description": "Source an R file"
+	},
+	"ret": {
+        "prefix": "ret",
+        "body": "return(${1:code})",
+		"description": "Return a value from a function"
+	},
+	"mat": {
+        "prefix": "mat",
+        "body": "matrix(${1:data}, nrow = ${2:rows}, ncol = ${3:cols})",
+		"description": "Define a matrix"
+	},
+	"sg": {
+        "prefix": "sg",
+        "body": [
+		"setGeneric(\"${1:generic}\", function(${2:x, ...}) {",
+		"\tstandardGeneric(\"${1:generic}\")",
+		"})"
+        ],
+		"description": "Define a generic"
+	},
+	"sm": {
+        "prefix": "sm",
+        "body": [
+		"setMethod(\"${1:generic}\", ${2:class}, function(${2:x, ...}) {",
+		"\t${0}",
+		"})"
+        ],
+		"description": "Define a method for a generic function"
+	},
+	"sc": {
+        "prefix": "sc",
+        "body": "setClass(\"${1:Class}\", slots = c(${2:name = \"type\"}))",
+		"description": "Define a class definition"
+	},
+	"if": {
+        "prefix": "if",
+        "body": [
+		"if (${1:condition}) {",
+		"\t${0}",
+		"}"
+        ],
+		"description": "Conditional expression"
+	},
+	"el": {
+        "prefix": "el",
+        "body": [
+		"else {",
+		"\t${0}",
+		"}"
+        ],
+		"description": "Conditional expression"
+	},
+	"ei": {
+        "prefix": "ei",
+        "body": [
+		"else if (${1:condition}) {",
+		"\t${0}",
+		"}"
+        ],
+		"description": "Conditional expression"
+	},
+	"fun": {
+        "prefix": "fun",
+        "body": [
+		"${1:name} <- function(${2:variables}) {",
+		"\t${0}",
+		"}"
+        ],
+		"description": "Function skeleton"
+	},
+	"for": {
+        "prefix": "for",
+        "body": [
+		"for (${1:variable} in ${2:vector}) {",
+		"\t${0}",
+		"}"
+        ],
+		"description": "Define a loop"
+	},
+	"while": {
+        "prefix": "while",
+        "body": [
+		"while (${1:condition}) {",
+		"\t${0}",
+		"}"
+        ],
+		"description": "Define a loop"
+	},
+	"switch": {
+        "prefix": "switch",
+        "body": [
+		"switch (${1:object},",
+		"\t${2:case} = ${3:action}",
+		")"
+        ],
+		"description": "Define a switch statement"
+	},
+	"apply": {
+        "prefix": "apply",
+        "body": "apply(${1:array}, ${2:margin}, ${3:...})",
+		"description": "Use the apply family"
+	},
+	"lapply": {
+        "prefix": "lapply",
+        "body": "lapply(${1:list}, ${2:function})",
+		"description": "Use the apply family"
+	},
+	"sapply": {
+        "prefix": "sapply",
+        "body": "sapply(${1:list}, ${2:function})",
+		"description": "Use the apply family"
+	},
+	"mapply": {
+        "prefix": "mapply",
+        "body": "mapply(${1:function}, ${2:...})",
+		"description": "Use the apply family"
+	},
+	"tapply": {
+        "prefix": "tapply",
+        "body": "tapply(${1:vector}, ${2:index}, ${3:function})",
+		"description": "Use the apply family"
+	},
+	"vapply": {
+        "prefix": "vapply",
+        "body": "vapply(${1:list}, ${2:function}, FUN.VALUE = ${3:type}, ${4:...})",
+		"description": "Use the apply family"
+	},
+	"rapply": {
+        "prefix": "rapply",
+        "body": "rapply(${1:list}, ${2:function})",
+		"description": "Use the apply family"
+	},
+	"ts": {
+        "prefix": "ts",
+        "body": "`r paste(\"#\", date(), \"------------------------------\\n\")`",
+		"description": "Insert a datetime"
+	},
+	"shinyapp": {
+        "prefix": "shinyapp",
+        "body": [
+		"library(shiny)",
+		"",
+		"ui <- fluidPage(",
+		"  ${0}",
+		")",
+		"",
+		"server <- function(input, output, session) {",
+		"  ",
+		"}",
+		"",
+		"shinyApp(ui, server)"
+        ],
+		"description": "Define a Shiny app"
+	},
+	"shinymod": {
+        "prefix": "shinymod",
+        "body": [
+		"${1:name}_UI <- function(id) {",
+		"  ns <- NS(id)",
+		"  tagList(",
+		"\t${0}",
+		"  )",
+		"}",
+		"",
+		"${1:name} <- function(input, output, session) {",
+		"  ",
+		"}"
+        ],
+		"description": "Define a Shiny module"
+	}
+}

crates/ark/src/lsp/completions/sources/composite.rs

@@ -10,6 +10,7 @@ mod document;
 mod keyword;
 mod pipe;
 mod search_path;
+mod snippets;
 mod subset;
 mod workspace;
 
@@ -22,6 +23,7 @@ use keyword::completions_from_keywords;
 use pipe::completions_from_pipe;
 use pipe::find_pipe_root;
 use search_path::completions_from_search_path;
+use snippets::completions_from_snippets;
 use stdext::*;
 use subset::completions_from_subset;
 use tower_lsp::lsp_types::CompletionItem;
@@ -63,6 +65,7 @@ pub fn completions_from_composite_sources(
     // anything.
     if context.node.kind() == "identifier" {
         completions.append(&mut completions_from_keywords());
+        completions.append(&mut completions_from_snippets());
         completions.append(&mut completions_from_search_path(context)?);
 
         if let Some(mut additional_completions) = completions_from_document(context)? {

crates/ark/src/lsp/completions/sources/composite/snippets.rs

@@ -0,0 +1,121 @@
+//
+// snippets.rs
+//
+// Copyright (C) 2023 Posit Software, PBC. All rights reserved.
+//
+//
+
+use std::collections::HashMap;
+use std::sync::Once;
+
+use rust_embed::RustEmbed;
+use serde::Deserialize;
+use tower_lsp::lsp_types::CompletionItem;
+use tower_lsp::lsp_types::CompletionItemKind;
+use tower_lsp::lsp_types::Documentation;
+use tower_lsp::lsp_types::InsertTextFormat;
+use tower_lsp::lsp_types::MarkupContent;
+use tower_lsp::lsp_types::MarkupKind;
+
+use crate::lsp::completions::completion_item::completion_item;
+use crate::lsp::completions::types::CompletionData;
+
+#[derive(RustEmbed)]
+#[folder = "resources/snippets/"]
+struct Asset;
+
+#[derive(Deserialize)]
+struct Snippet {
+    prefix: String,
+    body: SnippetBody,
+    description: String,
+}
+
+#[derive(Deserialize)]
+#[serde(untagged)]
+enum SnippetBody {
+    Scalar(String),
+    Vector(Vec<String>),
+}
+
+pub(super) fn completions_from_snippets() -> Vec<CompletionItem> {
+    log::info!("completions_from_snippets()");
+
+    // Return clone of cached snippet completion items
+    let completions = get_completions_from_snippets().clone();
+
+    completions
+}
+
+fn get_completions_from_snippets() -> &'static Vec<CompletionItem> {
+    static INIT: Once = Once::new();
+    static mut SNIPPETS: Option<Vec<CompletionItem>> = None;
+
+    INIT.call_once(|| unsafe {
+        SNIPPETS = Some(init_completions_from_snippets());
+    });
+
+    unsafe { SNIPPETS.as_ref().unwrap() }
+}
+
+fn init_completions_from_snippets() -> Vec<CompletionItem> {
+    // Load snippets JSON from embedded file
+    let file = Asset::get("r.code-snippets").unwrap();
+    let snippets: HashMap<String, Snippet> = serde_json::from_slice(&file.data).unwrap();
+
+    let mut completions = vec![];
+
+    for snippet in snippets.values() {
+        let label = snippet.prefix.clone();
+        let details = snippet.description.clone();
+
+        let body = match &snippet.body {
+            SnippetBody::Scalar(body) => body.clone(),
+            SnippetBody::Vector(body) => body.join("\n"),
+        };
+
+        // Markup shows up in the quick suggestion documentation window,
+        // so you can see what the snippet expands to
+        let markup = vec!["```r", body.as_str(), "```"].join("\n");
+        let markup = MarkupContent {
+            kind: MarkupKind::Markdown,
+            value: markup,
+        };
+
+        let mut item =
+            completion_item(label, CompletionData::Snippet { text: body.clone() }).unwrap();
+
+        item.detail = Some(details);
+        item.documentation = Some(Documentation::MarkupContent(markup));
+        item.kind = Some(CompletionItemKind::SNIPPET);
+
+        item.insert_text = Some(body);
+        item.insert_text_format = Some(InsertTextFormat::SNIPPET);
+
+        completions.push(item);
+    }
+
+    completions
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::lsp::completions::sources::composite::snippets::completions_from_snippets;
+
+    #[test]
+    fn test_snippets() {
+        let snippets = completions_from_snippets();
+
+        // Hash map isn't stable with regards to ordering
+        let item = snippets.iter().find(|item| item.label == "lib").unwrap();
+        assert_eq!(item.detail, Some("Attach an R package".to_string()));
+        assert_eq!(item.insert_text, Some("library(${1:package})".to_string()));
+
+        // Multiline body
+        let item = snippets.iter().find(|item| item.label == "if").unwrap();
+        assert_eq!(
+            item.insert_text,
+            Some("if (${1:condition}) {\n\t${0}\n}".to_string())
+        );
+    }
+}