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+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you 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
+#
+# http://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.
+
+#' @include arrowExports.R
+
+.unary_function_map <- list(
+ # NOTE: Each of the R functions mapped here takes exactly *one* argument, maps
+ # *directly* to an Arrow C++ compute kernel, and does not require any
+ # non-default options to be specified. More complex R function mappings are
+ # defined in dplyr-functions.R.
+
+ # functions are arranged alphabetically by name within categories
+
+ # arithmetic functions
+ "abs" = "abs_checked",
+ "ceiling" = "ceil",
+ "floor" = "floor",
+ "log10" = "log10_checked",
+ "log1p" = "log1p_checked",
+ "log2" = "log2_checked",
+ "sign" = "sign",
+ # trunc is defined in dplyr-functions.R
+
+ # trigonometric functions
+ "acos" = "acos_checked",
+ "asin" = "asin_checked",
+ "cos" = "cos_checked",
+ "sin" = "sin_checked",
+ "tan" = "tan_checked",
+
+ # logical functions
+ "!" = "invert",
+
+ # string functions
+ # nchar is defined in dplyr-functions.R
+ "str_length" = "utf8_length",
+ # str_pad is defined in dplyr-functions.R
+ # str_sub is defined in dplyr-functions.R
+ # str_to_lower is defined in dplyr-functions.R
+ # str_to_title is defined in dplyr-functions.R
+ # str_to_upper is defined in dplyr-functions.R
+ # str_trim is defined in dplyr-functions.R
+ "stri_reverse" = "utf8_reverse",
+ # substr is defined in dplyr-functions.R
+ # substring is defined in dplyr-functions.R
+ "tolower" = "utf8_lower",
+ "toupper" = "utf8_upper",
+
+ # date and time functions
+ "day" = "day",
+ "hour" = "hour",
+ "isoweek" = "iso_week",
+ "epiweek" = "us_week",
+ "isoyear" = "iso_year",
+ "minute" = "minute",
+ "month" = "month",
+ "quarter" = "quarter",
+ # second is defined in dplyr-functions.R
+ # wday is defined in dplyr-functions.R
+ "yday" = "day_of_year",
+ "year" = "year",
+
+ # type conversion functions
+ "as.factor" = "dictionary_encode"
+)
+
+.binary_function_map <- list(
+ # NOTE: Each of the R functions/operators mapped here takes exactly *two*
+ # arguments. Most map *directly* to an Arrow C++ compute kernel and require no
+ # non-default options, but some are modified by build_expr(). More complex R
+ # function/operator mappings are defined in dplyr-functions.R.
+ "==" = "equal",
+ "!=" = "not_equal",
+ ">" = "greater",
+ ">=" = "greater_equal",
+ "<" = "less",
+ "<=" = "less_equal",
+ "&" = "and_kleene",
+ "|" = "or_kleene",
+ "+" = "add_checked",
+ "-" = "subtract_checked",
+ "*" = "multiply_checked",
+ "/" = "divide",
+ "%/%" = "divide_checked",
+ # we don't actually use divide_checked with `%%`, rather it is rewritten to
+ # use `%/%` above.
+ "%%" = "divide_checked",
+ "^" = "power_checked",
+ "%in%" = "is_in_meta_binary"
+)
+
+.array_function_map <- c(.unary_function_map, .binary_function_map)
+
+#' Arrow expressions
+#'
+#' @description
+#' `Expression`s are used to define filter logic for passing to a [Dataset]
+#' [Scanner].
+#'
+#' `Expression$scalar(x)` constructs an `Expression` which always evaluates to
+#' the provided scalar (length-1) R value.
+#'
+#' `Expression$field_ref(name)` is used to construct an `Expression` which
+#' evaluates to the named column in the `Dataset` against which it is evaluated.
+#'
+#' `Expression$create(function_name, ..., options)` builds a function-call
+#' `Expression` containing one or more `Expression`s.
+#' @name Expression
+#' @rdname Expression
+#' @export
+Expression <- R6Class("Expression",
+ inherit = ArrowObject,
+ public = list(
+ ToString = function() compute___expr__ToString(self),
+ Equals = function(other, ...) {
+ inherits(other, "Expression") && compute___expr__equals(self, other)
+ },
+ # TODO: Implement type determination without storing
+ # schemas in Expression objects (ARROW-13186)
+ schema = NULL,
+ type = function(schema = self$schema) {
+ assert_that(!is.null(schema))
+ compute___expr__type(self, schema)
+ },
+ type_id = function(schema = self$schema) {
+ assert_that(!is.null(schema))
+ compute___expr__type_id(self, schema)
+ },
+ cast = function(to_type, safe = TRUE, ...) {
+ opts <- list(
+ to_type = to_type,
+ allow_int_overflow = !safe,
+ allow_time_truncate = !safe,
+ allow_float_truncate = !safe
+ )
+ Expression$create("cast", self, options = modifyList(opts, list(...)))
+ }
+ ),
+ active = list(
+ field_name = function() compute___expr__get_field_ref_name(self)
+ )
+)
+Expression$create <- function(function_name,
+ ...,
+ args = list(...),
+ options = empty_named_list()) {
+ assert_that(is.string(function_name))
+ assert_that(is_list_of(args, "Expression"), msg = "Expression arguments must be Expression objects")
+ expr <- compute___expr__call(function_name, args, options)
+ expr$schema <- unify_schemas(schemas = lapply(args, function(x) x$schema))
+ expr
+}
+
+Expression$field_ref <- function(name) {
+ assert_that(is.string(name))
+ compute___expr__field_ref(name)
+}
+Expression$scalar <- function(x) {
+ expr <- compute___expr__scalar(Scalar$create(x))
+ expr$schema <- schema()
+ expr
+}
+
+# Wrapper around Expression$create that:
+# (1) maps R function names to Arrow C++ compute ("/" --> "divide_checked")
+# (2) wraps R input args as Array or Scalar
+build_expr <- function(FUN,
+ ...,
+ args = list(...),
+ options = empty_named_list()) {
+ if (FUN == "-" && length(args) == 1L) {
+ if (inherits(args[[1]], c("ArrowObject", "Expression"))) {
+ return(build_expr("negate_checked", args[[1]]))
+ } else {
+ return(-args[[1]])
+ }
+ }
+ if (FUN == "%in%") {
+ # Special-case %in%, which is different from the Array function name
+ expr <- Expression$create("is_in", args[[1]],
+ options = list(
+ # If args[[2]] is already an Arrow object (like a scalar),
+ # this wouldn't work
+ value_set = Array$create(args[[2]]),
+ skip_nulls = TRUE
+ )
+ )
+ } else {
+ args <- lapply(args, function(x) {
+ if (!inherits(x, "Expression")) {
+ x <- Expression$scalar(x)
+ }
+ x
+ })
+
+ # In Arrow, "divide" is one function, which does integer division on
+ # integer inputs and floating-point division on floats
+ if (FUN == "/") {
+ # TODO: omg so many ways it's wrong to assume these types
+ args <- lapply(args, function(x) x$cast(float64()))
+ } else if (FUN == "%/%") {
+ # In R, integer division works like floor(float division)
+ out <- build_expr("/", args = args)
+ return(out$cast(int32(), allow_float_truncate = TRUE))
+ } else if (FUN == "%%") {
+ return(args[[1]] - args[[2]] * (args[[1]] %/% args[[2]]))
+ }
+
+ expr <- Expression$create(.array_function_map[[FUN]] %||% FUN, args = args, options = options)
+ }
+ expr
+}
+
+#' @export
+Ops.Expression <- function(e1, e2) {
+ if (.Generic == "!") {
+ build_expr(.Generic, e1)
+ } else {
+ build_expr(.Generic, e1, e2)
+ }
+}
+
+#' @export
+is.na.Expression <- function(x) {
+ Expression$create("is_null", x, options = list(nan_is_null = TRUE))
+}
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