From 94894068794dbb99804cda689b6c37e70376c8ca Mon Sep 17 00:00:00 2001 From: Gregory Anders Date: Wed, 19 Apr 2023 07:05:04 -0600 Subject: [PATCH] fix(iter): remove special case totable for map-like tables This was originally meant as a convenience but prevents possible functionality. For example: -- Get the keys of the table with even values local t = { a = 1, b = 2, c = 3, d = 4 } vim.iter(t):map(function(k, v) if v % 2 == 0 then return k end end):totable() The example above would not work, because the map() function returns only a single value, and cannot be converted back into a table (there are many such examples like this). Instead, to convert an iterator into a map-like table, users can use fold(): vim.iter(t):fold({}, function(t, k, v) t[k] = v return t end) --- runtime/doc/lua.txt | 23 +++++++++-- runtime/lua/vim/iter.lua | 67 +++++++++++--------------------- test/functional/lua/vim_spec.lua | 11 ++++-- 3 files changed, 50 insertions(+), 51 deletions(-) diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt index 60067f1bc3..8e68e9a792 100644 --- a/runtime/doc/lua.txt +++ b/runtime/doc/lua.txt @@ -3037,6 +3037,19 @@ Iter:find({self}, {f}) *Iter:find()* Iter:fold({self}, {init}, {f}) *Iter:fold()* Fold an iterator or table into a single value. + Examples: > + + -- Create a new table with only even values + local t = { a = 1, b = 2, c = 3, d = 4 } + local it = vim.iter(t) + it:filter(function(k, v) return v % 2 == 0 end) + it:fold({}, function(t, k, v) + t[k] = v + return t + end) + -- { b = 2, d = 4 } +< + Parameters: ~ • {init} any Initial value of the accumulator. • {f} function(acc:any, ...):A Accumulation function. @@ -3297,9 +3310,7 @@ Iter:totable({self}) *Iter:totable()* The resulting table depends on the initial source in the iterator pipeline. List-like tables and function iterators will be collected into a list-like table. If multiple values are returned from the final stage in - the iterator pipeline, each value will be included in a table. If a - map-like table was used as the initial source, then a map-like table is - returned. + the iterator pipeline, each value will be included in a table. Examples: >lua @@ -3310,9 +3321,13 @@ Iter:totable({self}) *Iter:totable()* -- { { 1, 2 }, { 2, 4 }, { 3, 6 } } vim.iter({ a = 1, b = 2, c = 3 }):filter(function(k, v) return v % 2 ~= 0 end):totable() - -- { a = 1, c = 3 } + -- { { 'a', 1 }, { 'c', 3 } } < + The generated table is a list-like table with consecutive, numeric + indices. To create a map-like table with arbitrary keys, use + |Iter:fold()|. + Return: ~ (table) diff --git a/runtime/lua/vim/iter.lua b/runtime/lua/vim/iter.lua index fff7644b6a..c5d5ef835b 100644 --- a/runtime/lua/vim/iter.lua +++ b/runtime/lua/vim/iter.lua @@ -18,14 +18,6 @@ ListIter.__call = function(self) return self:next() end ---- Special case implementations for iterators on non-list tables. ----@class TableIter : Iter -local TableIter = {} -TableIter.__index = setmetatable(TableIter, Iter) -TableIter.__call = function(self) - return self:next() -end - ---@private local function unpack(t) if type(t) == 'table' and t.__n ~= nil then @@ -185,10 +177,10 @@ end --- Collect the iterator into a table. --- ---- The resulting table depends on the initial source in the iterator pipeline. List-like tables ---- and function iterators will be collected into a list-like table. If multiple values are returned ---- from the final stage in the iterator pipeline, each value will be included in a table. If a ---- map-like table was used as the initial source, then a map-like table is returned. +--- The resulting table depends on the initial source in the iterator pipeline. +--- List-like tables and function iterators will be collected into a list-like +--- table. If multiple values are returned from the final stage in the iterator +--- pipeline, each value will be included in a table. --- --- Examples: --- 
lua
@@ -199,9 +191,13 @@ end
 --- -- { { 1, 2 }, { 2, 4 }, { 3, 6 } }
 ---
 --- vim.iter({ a = 1, b = 2, c = 3 }):filter(function(k, v) return v % 2 ~= 0 end):totable()
---- -- { a = 1, c = 3 }
+--- -- { { 'a', 1 }, { 'c', 3 } }
 ---
--- +--- The generated table is a list-like table with consecutive, numeric indices. +--- To create a map-like table with arbitrary keys, use |Iter:fold()|. +--- +--- ---@return table function Iter.totable(self) local t = {} @@ -239,17 +235,21 @@ function ListIter.totable(self) return Iter.totable(self) end ----@private -function TableIter.totable(self) - local t = {} - for k, v in self do - t[k] = v - end - return t -end - --- Fold an iterator or table into a single value. --- +--- Examples: +--- 
+--- -- Create a new table with only even values
+--- local t = { a = 1, b = 2, c = 3, d = 4 }
+--- local it = vim.iter(t)
+--- it:filter(function(k, v) return v % 2 == 0 end)
+--- it:fold({}, function(t, k, v)
+---   t[k] = v
+---   return t
+--- end)
+--- -- { b = 2, d = 4 }
+---
+--- ---@generic A --- ---@param init A Initial value of the accumulator. @@ -783,7 +783,7 @@ function Iter.new(src, ...) count = count + 1 local v = src[count] if v == nil then - return TableIter.new(src) + return Iter.new(pairs(src)) end t[count] = v end @@ -827,25 +827,4 @@ function ListIter.new(t) return it end ---- Create a new TableIter ---- ----@param t table Table to iterate over. For list-like tables, use ListIter.new instead. ----@return Iter ----@private -function TableIter.new(t) - local it = {} - - local index = nil - function it.next() - local k, v = next(t, index) - if k ~= nil then - index = k - return k, v - end - end - - setmetatable(it, TableIter) - return it -end - return Iter diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua index 07b0f0340a..e37d477376 100644 --- a/test/functional/lua/vim_spec.lua +++ b/test/functional/lua/vim_spec.lua @@ -3374,13 +3374,18 @@ describe('lua stdlib', function() end) it('handles map-like tables', function() - local t = { a = 1, b = 2, c = 3 } - local it = vim.iter(t):map(function(k, v) + local it = vim.iter({ a = 1, b = 2, c = 3 }):map(function(k, v) if v % 2 ~= 0 then return k:upper(), v * 2 end end) - eq({ A = 2, C = 6 }, it:totable()) + + local t = it:fold({}, function(t, k, v) + t[k] = v + return t + end) + eq({ A = 2, C = 6 }, t) + end) it('handles table values mid-pipeline', function() local map = {