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Better support for string matching in Snowflake #1406

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merged 5 commits into from
Dec 20, 2023
Merged

Better support for string matching in Snowflake #1406

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f67a525
Better support for stringr in Snowflake
nathanhaigh Nov 10, 2023
70b6007
Moved str_detect() over to REGEXP_INSTR
nathanhaigh Nov 11, 2023
fa76df8
Better grepl support for Snowflake
nathanhaigh Nov 14, 2023
72bf315
Ensure escape characters are escaped
nathanhaigh Nov 23, 2023
1335872
Better suport for string matching in Snowflake (#1406)
nathanhaigh Dec 19, 2023
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63 changes: 41 additions & 22 deletions R/backend-snowflake.R
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Original file line number Diff line number Diff line change
Expand Up @@ -38,23 +38,38 @@ sql_translation.Snowflake <- function(con) {
str_locate = function(string, pattern) {
sql_expr(POSITION(!!pattern, !!string))
},
# REGEXP on Snowflaake "implicitly anchors a pattern at both ends", which
# str_detect does not. Left- and right-pad `pattern` with .* to get
# str_detect-like behavior
str_detect = function(string, pattern, negate = FALSE) {
sql_str_pattern_switch(
string = string,
pattern = {{ pattern }},
negate = negate,
f_fixed = sql_str_detect_fixed_instr("detect"),
f_regex = function(string, pattern, negate = FALSE) {
if (isTRUE(negate)) {
sql_expr(!(((!!string)) %REGEXP% (".*" || (!!pattern) || ".*")))
} else {
sql_expr(((!!string)) %REGEXP% (".*" || (!!pattern) || ".*"))
}
}
)
con <- sql_current_con()

# Snowflake needs backslashes escaped, so we must increase the level of escaping
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
if (negate) {
translate_sql(REGEXP_INSTR(!!string, !!pattern) == 0L, con = con)
} else {
translate_sql(REGEXP_INSTR(!!string, !!pattern) != 0L, con = con)
}
},
str_starts = function(string, pattern, negate = FALSE) {
con <- sql_current_con()

# Snowflake needs backslashes escaped, so we must increase the level of escaping
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
if (negate) {
translate_sql(REGEXP_INSTR(!!string, !!pattern) != 1L, con = con)
} else {
translate_sql(REGEXP_INSTR(!!string, !!pattern) == 1L, con = con)
}
},
str_ends = function(string, pattern, negate = FALSE) {
con <- sql_current_con()

# Snowflake needs backslashes escaped, so we must increase the level of escaping
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
if (negate) {
translate_sql(REGEXP_INSTR(!!string, !!pattern, 1L, 1L, 1L) != LENGTH(!!string) + 1L, con = con)
} else {
translate_sql(REGEXP_INSTR(!!string, !!pattern, 1L, 1L, 1L) == LENGTH(!!string) + 1L, con = con)
}
},
# On Snowflake, REGEXP_REPLACE is used like this:
# REGEXP_REPLACE( <subject> , <pattern> [ , <replacement> ,
Expand Down Expand Up @@ -261,15 +276,19 @@ snowflake_grepl <- function(pattern,
perl = FALSE,
fixed = FALSE,
useBytes = FALSE) {
# https://docs.snowflake.com/en/sql-reference/functions/regexp.html
check_unsupported_arg(ignore.case, FALSE, backend = "Snowflake")
con <- sql_current_con()

check_unsupported_arg(perl, FALSE, backend = "Snowflake")
check_unsupported_arg(fixed, FALSE, backend = "Snowflake")
check_unsupported_arg(useBytes, FALSE, backend = "Snowflake")
# REGEXP on Snowflaake "implicitly anchors a pattern at both ends", which
# grepl does not. Left- and right-pad `pattern` with .* to get grepl-like
# behavior
sql_expr(((!!x)) %REGEXP% (".*" || !!paste0("(", pattern, ")") || ".*"))

# https://docs.snowflake.com/en/sql-reference/functions/regexp_instr.html
# REGEXP_INSTR optional parameters: position, occurrance, option, regex_parameters
regexp_parameters <- "c"
if(ignore.case) { regexp_parameters <- "i" }
# Snowflake needs backslashes escaped, so we must increase the level of escaping
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
translate_sql(REGEXP_INSTR(!!x, !!pattern, 1L, 1L, 0L, !!regexp_parameters) != 0L, con = con)
}

snowflake_round <- function(x, digits = 0L) {
Expand Down
10 changes: 0 additions & 10 deletions tests/testthat/_snaps/backend-snowflake.md
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@@ -1,13 +1,3 @@
# custom scalar translated correctly

Code
(expect_error(test_translate_sql(grepl("exp", x, ignore.case = TRUE))))
Output
<error/rlang_error>
Error in `grepl()`:
! `ignore.case = TRUE` isn't supported in Snowflake translation.
i It must be FALSE instead.

# pmin() and pmax() respect na.rm

Code
Expand Down
12 changes: 8 additions & 4 deletions tests/testthat/test-backend-snowflake.R
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,8 @@ test_that("custom scalar translated correctly", {
local_con(simulate_snowflake())
expect_equal(test_translate_sql(log10(x)), sql("LOG(10.0, `x`)"))
expect_equal(test_translate_sql(round(x, digits = 1.1)), sql("ROUND((`x`) :: FLOAT, 1)"))
expect_equal(test_translate_sql(grepl("exp", x)), sql("(`x`) REGEXP ('.*' || '(exp)' || '.*')"))
expect_snapshot((expect_error(test_translate_sql(grepl("exp", x, ignore.case = TRUE)))))
expect_equal(test_translate_sql(grepl("exp", x)), sql("REGEXP_INSTR(`x`, 'exp', 1, 1, 0, 'c') != 0"))
expect_equal(test_translate_sql(grepl("exp", x, ignore.case = TRUE)), sql("REGEXP_INSTR(`x`, 'exp', 1, 1, 0, 'i') != 0"))
})

test_that("pasting translated correctly", {
Expand All @@ -25,15 +25,19 @@ test_that("custom stringr functions translated correctly", {
local_con(simulate_snowflake())

expect_equal(test_translate_sql(str_locate(x, y)), sql("POSITION(`y`, `x`)"))
expect_equal(test_translate_sql(str_detect(x, y)), sql("(`x`) REGEXP ('.*' || `y` || '.*')"))
expect_equal(test_translate_sql(str_detect(x, y, negate = TRUE)), sql("!((`x`) REGEXP ('.*' || `y` || '.*'))"))
expect_equal(test_translate_sql(str_detect(x, y)), sql("REGEXP_INSTR(`x`, `y`) != 0"))
expect_equal(test_translate_sql(str_detect(x, y, negate = TRUE)), sql("REGEXP_INSTR(`x`, `y`) = 0"))
expect_equal(test_translate_sql(str_replace(x, y, z)), sql("REGEXP_REPLACE(`x`, `y`, `z`, 1.0, 1.0)"))
expect_equal(test_translate_sql(str_replace(x, "\\d", z)), sql("REGEXP_REPLACE(`x`, '\\\\d', `z`, 1.0, 1.0)"))
expect_equal(test_translate_sql(str_replace_all(x, y, z)), sql("REGEXP_REPLACE(`x`, `y`, `z`)"))
expect_equal(test_translate_sql(str_squish(x)), sql("REGEXP_REPLACE(TRIM(`x`), '\\\\s+', ' ')"))
expect_equal(test_translate_sql(str_remove(x, y)), sql("REGEXP_REPLACE(`x`, `y`, '', 1.0, 1.0)"))
expect_equal(test_translate_sql(str_remove_all(x, y)), sql("REGEXP_REPLACE(`x`, `y`)"))
expect_equal(test_translate_sql(str_trim(x)), sql("TRIM(`x`)"))
expect_equal(test_translate_sql(str_starts(x, y)), sql("REGEXP_INSTR(`x`, `y`) = 1"))
expect_equal(test_translate_sql(str_starts(x, y, negate = TRUE)), sql("REGEXP_INSTR(`x`, `y`) != 1"))
expect_equal(test_translate_sql(str_ends(x, y)), sql("REGEXP_INSTR(`x`, `y`, 1, 1, 1) = (LENGTH(`x`) + 1)"))
expect_equal(test_translate_sql(str_ends(x, y, negate = TRUE)), sql("REGEXP_INSTR(`x`, `y`, 1, 1, 1) != (LENGTH(`x`) + 1)"))
})

test_that("aggregates are translated correctly", {
Expand Down
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