{ "file":
  { "doc": ["Replace a file, logically in place, by a patched version"]
  , "target_fields": ["src", "patch"]
  , "string_fields": ["patch-part"]
  , "config_vars": ["PATCH", "ENV"]
  , "field_doc":
    { "src":
      [ "The single source file to patch, typically an explicit file reference."
      ]
    , "patch": ["The patch to apply."]
    , "patch-part":
      [ "If the patch contains hunks for multiple files, only apply hunks for"
      , "the specified file path. Individual directory components are joined"
      , "with \"/\". Note that the patch must be provided in unified format."
      ]
    }
  , "artifacts_doc":
    ["The patched file, staged to the position the of the original file"]
  , "runfiles_doc": ["Same as artifacts"]
  , "imports":
    { "stage_field": ["./", "..", "stage_singleton_field"]
    , "stage_artifact": ["./", "..", "stage_artifact_to_singleton_field"]
    }
  , "expression":
    { "type": "let*"
    , "bindings":
      [ [ "orig"
        , { "type": "let*"
          , "bindings": [["fieldname", "src"], ["location", "orig"]]
          , "body": {"type": "CALL_EXPRESSION", "name": "stage_field"}
          }
        ]
      , [ "patch"
        , { "type": "let*"
          , "bindings": [["fieldname", "patch"], ["location", "patch"]]
          , "body": {"type": "CALL_EXPRESSION", "name": "stage_field"}
          }
        ]
      , [ "patch-part"
        , { "type": "join"
          , "separator": "\\/"
          , "$1": {"type": "FIELD", "name": "patch-part"}
          }
        ]
      , [ "splitpatch"
        , { "type": "BLOB"
          , "data":
            { "type": "join"
            , "separator": "\n"
            , "$1":
              [ "set -e"
              , { "type": "join"
                , "$1":
                  [ { "type": "join_cmd"
                    , "$1":
                      [ "sed"
                      , "-n"
                      , { "type": "join"
                        , "$1":
                          [ "/^--- "
                          , {"type": "var", "name": "patch-part"}
                          , "/,"
                          , "/^[^-+@\\ ]\\|^---\\ /p"
                          ]
                        }
                      ]
                    }
                  , " $1 | sed '$d' > patch"
                  ]
                }
              ]
            }
          }
        ]
      , [ "patch"
        , { "type": "if"
          , "cond": {"type": "var", "name": "patch-part"}
          , "then":
            { "type": "ACTION"
            , "inputs":
              { "type": "map_union"
              , "$1":
                [ { "type": "to_subdir"
                  , "subdir": "in"
                  , "$1": {"type": "var", "name": "patch"}
                  }
                , { "type": "singleton_map"
                  , "key": "splitpatch"
                  , "value": {"type": "var", "name": "splitpatch"}
                  }
                ]
              }
            , "outs": ["patch"]
            , "cmd": ["sh", "./splitpatch", "in/patch"]
            , "env":
              {"type": "var", "name": "ENV", "default": {"type": "empty_map"}}
            }
          , "else": {"type": "var", "name": "patch"}
          }
        ]
      , [ "inputs"
        , { "type": "map_union"
          , "$1":
            [{"type": "var", "name": "orig"}, {"type": "var", "name": "patch"}]
          }
        ]
      , [ "patched"
        , { "type": "ACTION"
          , "inputs": {"type": "var", "name": "inputs"}
          , "outs": ["patched"]
          , "cmd":
            [ {"type": "var", "name": "PATCH", "default": "patch"}
            , "-s"
            , "--read-only=ignore"
            , "--follow-symlinks"
            , "-o"
            , "patched"
            , "orig"
            , "patch"
            ]
          }
        ]
      , [ "result"
        , { "type": "let*"
          , "bindings":
            [ ["artifact", {"type": "var", "name": "patched"}]
            , ["fieldname", "src"]
            ]
          , "body": {"type": "CALL_EXPRESSION", "name": "stage_artifact"}
          }
        ]
      ]
    , "body":
      { "type": "RESULT"
      , "artifacts": {"type": "var", "name": "result"}
      , "runfiles": {"type": "var", "name": "result"}
      }
    }
  }
}