bcbcf50442
Implements "gaps" in string literals. These are escape sequences of the
form `"\" newline whitespace+` that have the interpretation of an empty
string. For example,
```
"this is \
a string"
```
is equivalent to `"this is a string"`. These are modeled after string
continuations in
[Rust](https://doc.rust-lang.org/beta/reference/tokens.html#string-literals).
Implements RFC #2838
140 lines
2.8 KiB
Text
140 lines
2.8 KiB
Text
import Lean.Parser.Extension
|
|
import Lean.Elab.Term
|
|
|
|
/-!
|
|
# Testing string gaps in string literals
|
|
|
|
String gaps are described in RFC #2838
|
|
-/
|
|
|
|
/-!
|
|
A string gap with no trailing space.
|
|
-/
|
|
#eval "a\
|
|
b"
|
|
|
|
/-!
|
|
A string gap with trailing space before the `b`, which is consumed.
|
|
-/
|
|
#eval "a\
|
|
b"
|
|
|
|
/-!
|
|
A string gap with space before the gap, which is not consumed.
|
|
-/
|
|
#eval "a \
|
|
b"
|
|
|
|
/-!
|
|
Multiple string gaps in a row.
|
|
-/
|
|
#eval "a \
|
|
\
|
|
\
|
|
b"
|
|
|
|
/-!
|
|
Two tests from the RFC.
|
|
-/
|
|
#eval "this is \
|
|
a string"
|
|
#eval "this is \
|
|
a string"
|
|
|
|
/-!
|
|
Two examples of how spaces are accounted for in string gaps. `\x20` is a way to force a leading space.
|
|
-/
|
|
#eval "there are three spaces between the brackets < \
|
|
>"
|
|
#eval "there are three spaces between the brackets <\
|
|
\x20 >"
|
|
|
|
/-!
|
|
Using `\n` to terminate a string gap, which is a technique suggested by Mario for using string gaps to write
|
|
multiline literals in an indented context.
|
|
-/
|
|
#eval "this is\
|
|
\n a string with two space indent"
|
|
|
|
/-!
|
|
Similar tests but for interpolated strings.
|
|
-/
|
|
#eval s!"a\
|
|
b"
|
|
#eval s!"a\
|
|
b"
|
|
#eval s!"a\
|
|
b"
|
|
|
|
/-!
|
|
The `{` terminates the string gap.
|
|
-/
|
|
#eval s!"a\
|
|
{"b"}\
|
|
"
|
|
|
|
open Lean
|
|
|
|
/-!
|
|
## Testing whitespace handling with specific line terminators
|
|
-/
|
|
|
|
/-!
|
|
Standard string gap, with LF
|
|
-/
|
|
#eval show MetaM String from do
|
|
let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\\n b\""
|
|
let some s := stx.isStrLit? | failure
|
|
return s
|
|
|
|
/-!
|
|
Standard string gap, with CRLF
|
|
-/
|
|
#eval show MetaM String from do
|
|
let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\\r\n b\""
|
|
let some s := stx.isStrLit? | failure
|
|
return s
|
|
|
|
/-!
|
|
Isolated CR, which is an error
|
|
-/
|
|
#eval show MetaM String from do
|
|
let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\\r b\""
|
|
let some s := stx.isStrLit? | failure
|
|
return s
|
|
|
|
/-!
|
|
Not a string gap since there's no end-of-line.
|
|
-/
|
|
#eval show MetaM String from do
|
|
let stx ← ofExcept <| Parser.runParserCategory (← getEnv) `term "\"a\\ b\""
|
|
let some s := stx.isStrLit? | failure
|
|
return s
|
|
|
|
/-!
|
|
## Scala-style stripMargin
|
|
|
|
This is a test that string gaps could be paired with a new string elaboration syntax
|
|
for indented multiline string literals.
|
|
-/
|
|
|
|
def String.dedent (s : String) : Option String :=
|
|
let parts := s.split (· == '\n') |>.map String.trimLeft
|
|
match parts with
|
|
| [] => ""
|
|
| [p] => p
|
|
| p₀ :: parts =>
|
|
if !parts.all (·.startsWith "|") then
|
|
none
|
|
else
|
|
p₀ ++ "\n" ++ String.intercalate "\n" (parts.map fun p => p.drop 1)
|
|
|
|
elab "d!" s:str : term => do
|
|
let some s := s.raw.isStrLit? | Lean.Elab.throwIllFormedSyntax
|
|
let some s := String.dedent s | Lean.Elab.throwIllFormedSyntax
|
|
pure $ Lean.mkStrLit s
|
|
|
|
#eval d!"this is \
|
|
line 1
|
|
| line 2, indented
|
|
|line 3"
|