36 lines
1.6 KiB
Lua
36 lines
1.6 KiB
Lua
-- ( exp ) must truncate a multi-return to exactly one value (Lua 5.4 semantics).
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-- string.gsub returns 2 values (string, count); parens must drop the count.
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-- 1: parenthesized call yields arity 1
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assert(select("#", (string.gsub("a:b", ":", " "))) == 1, "paren call arity should be 1")
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-- 2: a function returning (multi) yields arity 1
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local function mk() return (string.gsub("a:b", ":", " ")) end
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assert(select("#", mk()) == 1, "return (multi) should yield arity 1")
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-- 3: table.insert with a parenthesized-returning call inserts exactly one element
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local t1 = {}
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table.insert(t1, mk())
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assert(#t1 == 1, "table.insert should add one element, got " .. #t1)
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assert(t1[1] == "a b", "inserted value should be the gsub string, got " .. tostring(t1[1]))
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-- 4: table.insert with an inline parenthesized gsub
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local t2 = {}
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table.insert(t2, (string.gsub("a:b", ":", " ")))
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assert(#t2 == 1, "inline paren insert should add one element, got " .. #t2)
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-- 5: contrast — binding to a local already worked; must still work
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local t3 = {}
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local v = mk()
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table.insert(t3, v)
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assert(#t3 == 1, "local-bound insert should add one element")
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-- 6: multiple assignment from a parenthesized multi-return drops extra values
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local a, b = (string.gsub("a:b", ":", " "))
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assert(a == "a b", "first value preserved")
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assert(b == nil, "parenthesized truncation should leave b nil, got " .. tostring(b))
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-- 7: an UNparenthesized trailing call must still expand (no regression)
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local function multi() return string.gsub("a:b", ":", " ") end
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assert(select("#", multi()) == 2, "unparenthesized return must still expand to 2")
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