fa5d08b7de
This PR redefines `String.take` and variants to operate on `String.Slice`. While previously functions returning a substring of the input sometimes returned `String` and sometimes returned `Substring.Raw`, they now uniformly return `String.Slice`. This is a BREAKING change, because many functions now have a different return type. So for example, if `s` is a string and `f` is a function accepting a string, `f (s.drop 1)` will no longer compile because `s.drop 1` is a `String.Slice`. To fix this, insert a call to `copy` to restore the old behavior: `f (s.drop 1).copy`. Of course, in many cases, there will be more efficient options. For example, don't write `f <| s.drop 1 |>.copy |>.dropEnd 1 |>.copy`, write `f <| s.drop 1 |>.dropEnd 1 |>.copy` instead. Also, instead of `(s.drop 1).copy = "Hello"`, write `s.drop 1 == "Hello".toSlice` instead.
166 lines
3.5 KiB
Text
166 lines
3.5 KiB
Text
import Lean.Parser.Extension
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import Lean.Elab.Term
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/-!
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# Testing string gaps in string literals
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String gaps are described in RFC #2838
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-/
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/-!
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A string gap with no trailing space.
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-/
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/-- info: "ab" -/
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#guard_msgs in
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#eval "a\
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b"
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/-!
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A string gap with trailing space before the `b`, which is consumed.
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-/
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/-- info: "ab" -/
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#guard_msgs in
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#eval "a\
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b"
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/-!
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A string gap with space before the gap, which is not consumed.
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-/
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/-- info: "a b" -/
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#guard_msgs in
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#eval "a \
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b"
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/-!
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Multiple string gaps in a row.
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-/
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/-- info: "a b" -/
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#guard_msgs in
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#eval "a \
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\
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\
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b"
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/-!
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Two tests from the RFC.
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-/
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/-- info: "this is a string" -/
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#guard_msgs in
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#eval "this is \
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a string"
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/-- info: "this is a string" -/
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#guard_msgs in
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#eval "this is \
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a string"
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/-!
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Two examples of how spaces are accounted for in string gaps. `\x20` is a way to force a leading space.
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-/
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/-- info: "there are three spaces between the brackets < >" -/
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#guard_msgs in
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#eval "there are three spaces between the brackets < \
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>"
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/-- info: "there are three spaces between the brackets < >" -/
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#guard_msgs in
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#eval "there are three spaces between the brackets <\
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\x20 >"
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/-!
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Using `\n` to terminate a string gap, which is a technique suggested by Mario for using string gaps to write
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multiline literals in an indented context.
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-/
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/-- info: "this is\n a string with two space indent" -/
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#guard_msgs in
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#eval "this is\
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\n a string with two space indent"
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/-!
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Similar tests but for interpolated strings.
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-/
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/-- info: "ab" -/
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#guard_msgs in
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#eval s!"a\
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b"
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/-- info: "ab" -/
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#guard_msgs in
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#eval s!"a\
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b"
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/-- info: "ab" -/
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#guard_msgs in
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#eval s!"a\
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b"
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/-!
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The `{` terminates the string gap.
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-/
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/-- info: "ab" -/
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#guard_msgs in
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#eval s!"a\
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{"b"}\
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"
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open Lean
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/-!
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## Testing whitespace handling with specific line terminators
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-/
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/-!
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Standard string gap, with LF
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-/
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/-- info: "ab" -/
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#guard_msgs in
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#eval show MetaM String from do
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let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\\n b\""
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let some s := stx.isStrLit? | failure
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return s
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/-!
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Isolated CR, which is an error
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-/
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/-- error: <input>:1:3: invalid escape sequence -/
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#guard_msgs (error, drop info) in
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#eval show MetaM String from do
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let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\\r b\""
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let some s := stx.isStrLit? | failure
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return s
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/-!
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Not a string gap since there's no end-of-line.
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-/
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/-- error: <input>:1:3: invalid escape sequence -/
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#guard_msgs (error, drop info) in
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#eval show MetaM String from do
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let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\ b\""
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let some s := stx.isStrLit? | failure
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return s
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/-!
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## Scala-style stripMargin
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This is a test that string gaps could be paired with a new string elaboration syntax
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for indented multiline string literals.
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-/
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def String.dedent (s : String) : Option String :=
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let parts := s.split (· == '\n') |>.map String.trimLeft
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match parts with
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| [] => ""
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| [p] => p
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| p₀ :: parts =>
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if !parts.all (·.startsWith "|") then
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none
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else
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p₀ ++ "\n" ++ String.intercalate "\n" (parts.map fun p => p.drop 1 |>.copy)
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elab "d!" s:str : term => do
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let some s := s.raw.isStrLit? | Lean.Elab.throwIllFormedSyntax
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let some s := String.dedent s | Lean.Elab.throwIllFormedSyntax
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pure $ Lean.mkStrLit s
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/-- info: "this is line 1\n line 2, indented\nline 3" -/
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#guard_msgs in
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#eval d!"this is \
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line 1
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| line 2, indented
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|line 3"
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