Implement snippet priority

doc/snippy.txt

@@ -8,15 +8,15 @@ CONTENTS                                                     *snippy-contents*
     INTRODUCTION.........................|snippy-introduction|
     USAGE................................|snippy-usage|
     FUNCTIONS............................|snippy-functions|
-    OPTIONS..............................|snippy-options|
+    SETUP OPTIONS........................|snippy-setup-options|
     COMMANDS.............................|snippy-commands|
     LICENSE..............................|snippy-license|
 
 
 ==============================================================================
 INTRODUCTION                                             *snippy-introduction*
 
-Snippy is a lua-based snippets plugin for Neovim.
+Snippy is a snippets plugin for Neovim written in Lua.
 
 
 ==============================================================================
@@ -25,9 +25,9 @@ USAGE                                                           *snippy-usage*
                                                           *snippy-usage-setup*
 
 Snippy includes an optional |snippy.setup()| function for you to quickly
-configure it according to your needs. See the |snippy-options| section for
-information on the available options. Below is an example showing most of the
-available options:
+configure it according to your needs. See the |snippy-setup-options| section
+for information on the available options. Below is an example showing most of
+the available options:
 >
     require('snippy').setup({
         snippet_dirs = '~/snippets',
@@ -93,7 +93,7 @@ be used later by the `$VISUAL` or `$TM_SELECTED_TEXT` variables:
 When mapping from Lua using |nvim_set_keymap()|, you can use
 |snippy.can_expand()| and |snippy.can_jump()| functions. The Vimscript
 functions above are just convenience wrappings around those. You can also map
-keys by using the `mappings` setup option (see |snippy-options|).
+keys by using the `mappings` setup option (see |snippy-setup-options|).
 
                                                        *snippy-usage-snippets*
 
@@ -148,12 +148,26 @@ This could also be achieved with an |autocmd|. Indenting with spaces is a
 Snippy feature and might not be compatible with other snippet plugins like
 SnipMate.
 
-Note: Snippy follows the |runtimepath| order when loading snippets, which
+                                                       *snippy-usage-priority*
+
+Snippy follows the |runtimepath| order when loading snippets, which
 means snippets defined in folders coming later in the list will always
 override those loaded before. So, if you put your custom snippets in
 `after/snippets/`, they should override any snippets provided by plugins in
 case of name conflict.
 
+Another way to determine which snippets should be loaded first is to use the
+`priority` directive, currently only possible in `.snippets` files. The
+default priority is 0, so you can set your own snippets' priority to a higher
+value, like 100, for them to override lower priority snippets. The priority
+directive affects all snippets listed after it:
+>
+    priority 100
+    snippet trigger1
+    	...
+    snippet trigger2
+    	...
+<
                                                          *snippy-usage-scopes*
 
 Scopes are the term used in Snippy to refer to a group of snippets that should
@@ -234,7 +248,7 @@ TextMate/LSP syntax.
 FUNCTIONS                                                   *snippy-functions*
 
 snippy.setup({options})                                       *snippy.setup()*
-    Set initial configuration for the plugin. See also |snippy-options|.
+    Set initial configuration for the plugin. See also |snippy-setup-options|.
 
 snippy.setup_buffer({bufnr}, {options})                *snippy.setup_buffer()*
     Set configuration for the current buffer. See also
@@ -308,9 +322,9 @@ snippy#can_expand_or_advance()                *snippy#can_expand_or_advance()*
 
 
 ==============================================================================
-OPTIONS                                                       *snippy-options*
+SETUP OPTIONS                                           *snippy-setup-options*
 
-This plugin can be configured by passing a dictionary to the lua function
+This plugin can be configured by passing a dictionary to the Lua function
 `snippy.setup(...)`. The following options are supported:
 
 snippet_dirs ~

lua/snippy/reader/snipmate.lua

@@ -42,6 +42,7 @@ end
 local function read_snippets_file(snippets_file)
     local snips = {}
     local extends = {}
+    local priority = 0
     local file = io.open(snippets_file)
     local lines = vim.split(file:read('*a'), '\n')
     if lines[#lines] == '' then
@@ -57,7 +58,7 @@ local function read_snippets_file(snippets_file)
         local option = description and parse_options(prefix, line) or {}
         if option.auto_trigger and not shared.config.enable_auto then
             local msg = [[[Snippy] Warning: you seem to have autotriggered snippets,]]
-                .. [[ but the autotrigger feature isn\'t enabled in your config.]]
+                .. [[ but the autotrigger feature isn't enabled in your config.]]
                 .. [[ See :help snippy-snippet-options for details.]]
             api.nvim_echo({ { msg, 'WarningMsg' } }, true, {})
         end
@@ -83,13 +84,16 @@ local function read_snippets_file(snippets_file)
                 break
             end
         end
-        snips[prefix] = {
-            kind = 'snipmate',
-            prefix = prefix,
-            description = description,
-            option = option,
-            body = body,
-        }
+        if not snips[prefix] or snips[prefix].priority <= priority then
+            snips[prefix] = {
+                kind = 'snipmate',
+                prefix = prefix,
+                priority = priority,
+                description = description,
+                option = option,
+                body = body,
+            }
+        end
     end
 
     while i <= #lines do
@@ -100,11 +104,18 @@ local function read_snippets_file(snippets_file)
             local scopes = vim.split(vim.trim(line:sub(8)), '%s+')
             vim.list_extend(extends, scopes)
             i = i + 1
+        elseif line:sub(1, 8) == 'priority' then
+            local prio = vim.trim(line:sub(9))
+            if not prio or not prio:match('-%d+') or not prio:match('+?%d+') then
+                error(string.format('Invalid priority in file %s, at line %s: %s', snippets_file, i, prio))
+            end
+            priority = tonumber(prio)
+            i = i + 1
         elseif line:sub(1, 1) == '#' or vim.trim(line) == '' then
             -- Skip empty lines or comments
             i = i + 1
         else
-            error(string.format('Invalid line in snippets file %s: %s', snippets_file, line))
+            error(string.format('Unrecognized syntax in snippets file %s, at line %s: %s', snippets_file, i, line))
         end
     end
     return snips, extends
@@ -128,6 +139,8 @@ local function read_snippet_file(snippet_file, scope)
             kind = 'snipmate',
             prefix = prefix,
             description = description,
+            -- Priority for .snippet is always 0
+            priority = 0,
             body = body,
         },
     }
@@ -156,6 +169,22 @@ local function list_files(ftype)
     return all
 end
 
+local function merge_snippets(current, added)
+    local result = vim.deepcopy(current)
+    for key, val in pairs(added) do
+        if current[key] then
+            local cur_snip = current[key]
+            local new_snip = added[key]
+            if new_snip.priority >= cur_snip.priority then
+                result[key] = val
+            end
+        else
+            result[key] = val
+        end
+    end
+    return result
+end
+
 local function load_scope(scope, stack)
     local snips = {}
     local extends = {}
@@ -168,7 +197,7 @@ local function load_scope(scope, stack)
         elseif file:match('.snippet$') then
             result = read_snippet_file(file, scope)
         end
-        snips = vim.tbl_extend('force', snips, result)
+        snips = merge_snippets(snips, result)
     end
     for _, extended in ipairs(extends) do
         if vim.tbl_contains(stack, extended) then
@@ -180,7 +209,7 @@ local function load_scope(scope, stack)
             )
         end
         local result = load_scope(extended, vim.tbl_flatten({ stack, scope }))
-        snips = vim.tbl_extend('keep', snips, result)
+        snips = merge_snippets(snips, result)
     end
     return snips
 end

test/unit/reader_spec.lua

@@ -9,8 +9,20 @@ describe('Snippet reader', function()
         snippy.setup({ snippet_dirs = './test/snippets/' })
         vim.cmd('set filetype=')
         local snips = {
-            test1 = { kind = 'snipmate', prefix = 'test1', option = {}, body = { 'This is the first test.' } },
-            test2 = { kind = 'snipmate', prefix = 'test2', option = {}, body = { 'This is the second test.' } },
+            test1 = {
+                kind = 'snipmate',
+                prefix = 'test1',
+                option = {},
+                priority = 0,
+                body = { 'This is the first test.' },
+            },
+            test2 = {
+                kind = 'snipmate',
+                prefix = 'test2',
+                option = {},
+                priority = 0,
+                body = { 'This is the second test.' },
+            },
         }
         assert.is_truthy(require('snippy.shared').config.snippet_dirs)
         assert.is_not.same({}, require('snippy.reader.snipmate').list_available_scopes())
@@ -24,6 +36,7 @@ describe('Snippet reader', function()
             no_description = {
                 kind = 'snipmate',
                 prefix = 'no_description',
+                priority = 0,
                 body = {
                     'This is a *.snippet file with no description.',
                 },
@@ -32,6 +45,7 @@ describe('Snippet reader', function()
                 kind = 'snipmate',
                 prefix = 'trigger',
                 description = 'description',
+                priority = 0,
                 body = {
                     'This is a *.snippet file with a description.',
                 },
@@ -50,6 +64,7 @@ describe('Snippet reader', function()
                 prefix = 'trigger',
                 option = {},
                 description = 'description',
+                priority = 0,
                 body = {
                     'This is indented with two spaces.',
                     '\tThis is indented with four spaces.',
@@ -63,7 +78,7 @@ describe('Snippet reader', function()
     end)
 
     it('can read snippets with otions', function()
-        snippy.setup({ snippet_dirs = './test/snippets/' })
+        snippy.setup({ snippet_dirs = './test/snippets/', enable_auto = true })
         vim.cmd('set filetype=java')
         assert.is_truthy(require('snippy.shared').config.snippet_dirs)
         assert.is_not.same({}, require('snippy.reader.snipmate').list_available_scopes())