// Copyright 2020 The Jujutsu Authors
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
// https://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Example:
// "commit: " ++ short(commit_id) ++ "\n"
// predecessors.map(|p| "predecessor: " ++ p.commit_id)
// parents.map(|p| p.commit_id ++ " is a parent of " ++ commit_id)

whitespace = _{ " " | "\t" | "\r" | "\n" | "\x0c" }

escape = @{ "\\" ~ ("t" | "r" | "n" | "\"" | "\\") }
literal_char = @{ !("\"" | "\\") ~ ANY }
raw_literal = @{ literal_char+ }
literal = { "\"" ~ (raw_literal | escape)* ~ "\"" }

integer_literal = {
  ASCII_NONZERO_DIGIT ~ ASCII_DIGIT*
  | "0"
}

identifier = @{ (ASCII_ALPHA | "_") ~ (ASCII_ALPHANUMERIC | "_")* }

function = { identifier ~ "(" ~ whitespace* ~ function_arguments ~ whitespace* ~ ")" }
function_arguments = {
  template ~ (whitespace* ~ "," ~ whitespace* ~ template)* ~ (whitespace* ~ ",")?
  | ""
}
lambda = {
  "|" ~ whitespace* ~ formal_parameters ~ whitespace* ~ "|"
  ~ whitespace* ~ template
}
formal_parameters = {
  identifier ~ (whitespace* ~ "," ~ whitespace* ~ identifier)* ~ (whitespace* ~ ",")?
  | ""
}

primary = _{
  ("(" ~ whitespace* ~ template ~ whitespace* ~ ")")
  | function
  | lambda
  | identifier
  | literal
  | integer_literal
}

term = {
  primary ~ ("." ~ function)*
}

concat = _{
  term ~ (whitespace* ~ "++" ~ whitespace* ~ term)+
}

template = { concat | term }

program = _{ SOI ~ whitespace* ~ template? ~ whitespace* ~ EOI }

function_alias_declaration = {
  identifier ~ "(" ~ whitespace* ~ formal_parameters ~ whitespace* ~ ")"
}
alias_declaration = _{
  SOI ~ (function_alias_declaration | identifier) ~ EOI
}