tbl

Table operations for querying, copying, merging, and transforming tables.

Usage

tbl = require "mods.tbl"

print(tbl.count({ a = 1, b = 2 })) --> 2

Functions

Basics:

Function	Description
clear(t)	Remove all entries from the table.
count(t)	Return the number of keys in the table.

Copying:

Function	Description
copy(t)	Create a shallow copy of the table.
deepcopy(v)	Create a deep copy of a value.

Query:

Function	Description
filter(t, pred)	Filter entries by a value predicate.
find(t, v)	Find the first key whose value equals the given value.
same(a, b)	Return true if two tables have the same keys and equal values.
find_if(t, pred)	Find first value and key matching predicate.
get(t, ...)	Safely get nested value by keys.

Transforms:

Function	Description
invert(t)	Invert keys/values into new table.
isempty(t)	Return true if table has no entries.
keys(t)	Return a list of all keys in the table.
map(t, fn)	Return a new table by mapping each value (keys preserved).
pairmap(t, fn)	Return a new table by mapping each key-value pair.
update(t1, t2)	Merge entries from t2 into t1 and return t1.
values(t)	Return a list of all values in the table.

Iteration:

Function	Description
foreach(t, fn)	Call a function for each value in the table.
spairs(t)	Iterate key-value pairs in sorted key order.

Basics

Core table utilities for clearing and counting.

clear(t)

Remove all entries from the table.

Parameters:

• t (table): Target table.

Return:

• none (nil)

Example:

t = { a = 1, b = 2 }
clear(t) --> t = {}

count(t)

Return the number of keys in the table.

Parameters:

• t (table): Input table.

Return:

• count (integer): Number of keys in t.

Example:

n = count({ a = 1, b = 2 }) --> 2

Copying

Shallow and deep copy helpers.

copy(t)

Create a shallow copy of the table.

Parameters:

• t (T): Source table.

Return:

• copy (T): Shallow-copied table.

Example:

t = copy({ a = 1, b = 2 }) --> { a = 1, b = 2 }

deepcopy(v)

Create a deep copy of a value.

Parameters:

• v (T): Input value.

Return:

• copiedValue (T): Deep-copied value.

Example:

t = deepcopy({ a = { b = 1 } }) --> { a = { b = 1 } }
n = deepcopy(42) --> 42

NOTE

If v is a table, all nested tables are copied recursively; other types are returned as-is.

Query

Read-only lookup and selection helpers.

filter(t, pred)

Filter entries by a value predicate.

Parameters:

• t (table<K,V>): Input table.
• pred (fun(value:V):boolean): Value predicate.

Return:

• filtered (table): Table containing entries where pred(v) is true.

Example:

even = filter({ a = 1, b = 2, c = 3 }, function(v)
  return v % 2 == 0
end) --> { b = 2 }

find(t, v)

Find the first key whose value equals the given value.

Parameters:

• t (table<K,V>): Input table.
• v (V): Value to find.

Return:

• key (K?): First matching key, or nil when not found.

Example:

key = find({ a = 1, b = 2, c = 2 }, 2) --> "b" or "c"

same(a, b)

Return true if two tables have the same keys and equal values.

Parameters:

• a (table): Left table.
• b (table): Right table.

Return:

• isSame (boolean): True when both tables have the same keys and values.

Example:

ok = same({ a = 1, b = 2 }, { b = 2, a = 1 }) --> true
ok = same({ a = {} }, { a = {} })             --> false

find_if(t, pred)

Find first value and key matching predicate.

Parameters:

• t (table): Input table.
• pred (fun(key:K,value:V):boolean): Predicate function.

Return:

• value (V?): First matching value, or nil when not found.
• key (K?): Key for the first matching value, or nil when not found.

Example:

v, k = find_if({ a = 1, b = 2 }, function(v, k)
  return k == "b" and v == 2
end) --> 2, "b"

get(t, ...)

Safely get nested value by keys.

Parameters:

• t (table): Root table.
• ... (any): Additional arguments.

Return:

• nestedValue (any): Nested value, or nil when any key is missing.

Example:

t = { a = { b = { c = 1 } } }
v1 = get(t, "a", "b", "c") --> 1
v2 = get(t)                --> { a = { b = { c = 1 } } }

NOTE

If no keys are provided, returns the input table.

Transforms

Table transformation and conversion utilities.

invert(t)

Invert keys/values into new table.

Parameters:

• t (table<K,V>): Input table.

Return:

• inverted (table<V,K>): Inverted table (value -> key).

Example:

t = invert({ a = 1, b = 2 }) --> { [1] = "a", [2] = "b" }

isempty(t)

Return true if table has no entries.

Parameters:

• t (table): Input table.

Return:

• isEmpty (boolean): True when t has no entries.

Example:

empty = isempty({}) --> true

keys(t)

Return a list of all keys in the table.

Parameters:

• t (table<K,V>): Input table.

Return:

• keys (mods.List<V>): List of keys in t.

Example:

keys = keys({ a = 1, b = 2 }) --> { "a", "b" }

map(t, fn)

Return a new table by mapping each value (keys preserved).

Parameters:

• t (table<K,V>): Input table.
• fn (fun(value:V):T): Mapping function.

Return:

• mapped (table<K,T>): New table with mapped values.

Example:

t = map({ a = 1, b = 2 }, function(v)
  return v * 10
end) --> { a = 10, b = 20 }

pairmap(t, fn)

Return a new table by mapping each key-value pair.

Parameters:

• t (table<K,V>): Input table.
• fn (fun(key:K, value:V):T): Key-value mapping function.

Return:

• mapped (table<K,T>): New table with mapped values.

Example:

t = pairmap({ a = 1, b = 2 }, function(k, v)
  return k .. v
end) --> { a = "a1", b = "b2" }

NOTE

Output keeps original keys; only values are transformed by fn.

update(t1, t2)

Merge entries from t2 into t1 and return t1.

Parameters:

• t1 (T): Target table.
• t2 (table): Source table.

Return:

• table (T): Updated t1 table.

Example:

t1 = { a = 1, b = 2 }
update(t1, { b = 3, c = 4 }) --> t1 is { a = 1, b = 3, c = 4 }

values(t)

Return a list of all values in the table.

Parameters:

• t (table<K,V>): Input table.

Return:

• values (mods.List<V>): List of values in t.

Example:

vals = values({ a = 1, b = 2 }) --> { 1, 2 }

Iteration

Iterators and ordered traversal helpers.

foreach(t, fn)

Call a function for each value in the table.

Parameters:

• t (table<K,V>): Input table.
• fn (fun(value:V, key:K)): Function invoked for each entry.

Return:

• none (nil)

Example:

foreach({ a = 1, b = 2 }, function(v, k)
  print(k, v)
end)

spairs(t)

Iterate key-value pairs in sorted key order.

Parameters:

• t (T): Input table.

Return:

• iterator (fun(table: table<K, V>, index?: K):(K, V)): Sorted pairs iterator.
• value (T)

Example:

for k, v in spairs({ b = 2, a = 1 }) do
  print(k, v)
end