// 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" }

string_escape = @{ "\\" ~ ("t" | "r" | "n" | "0" | "\"" | "\\") }
string_content_char = @{ !("\"" | "\\") ~ ANY }
string_content = @{ string_content_char+ }
string_literal = ${ "\"" ~ (string_content | string_escape)* ~ "\"" }

raw_string_content = @{ (!"'" ~ ANY)* }
raw_string_literal = ${ "'" ~ raw_string_content ~ "'" }

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

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

concat_op = { "++" }
logical_or_op = { "||" }
logical_and_op = { "&&" }
logical_not_op = { "!" }
negate_op = { "-" }
prefix_ops = _{ logical_not_op | negate_op }
infix_ops = _{ logical_or_op | logical_and_op }

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
  | string_literal
  | raw_string_literal
  | integer_literal
}

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

expression = {
  (prefix_ops ~ whitespace*)* ~ term
  ~ (whitespace* ~ infix_ops ~ whitespace* ~ (prefix_ops ~ whitespace*)* ~ term)*
}

template = {
  expression ~ (whitespace* ~ concat_op ~ whitespace* ~ expression)*
}

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

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