commit 94894068794dbb99804cda689b6c37e70376c8ca
parent 6b96122453fda22dc44a581af1d536988c1adf41
Author: Gregory Anders <greg@gpanders.com>
Date: Wed, 19 Apr 2023 07:05:04 -0600
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)
Diffstat:
3 files changed, 50 insertions(+), 51 deletions(-)
diff --git 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
@@ -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:
--- <pre>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 } }
--- </pre>
---
+--- 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:
+--- <pre>
+--- -- 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 }
+--- </pre>
+---
---@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
@@ -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 = {
