Sugar function 'trimws' with unit tests (closes #679)

ChangeLog

@@ -1,3 +1,11 @@
+2017-04-22  Nathan Russell  <russell.nr2012@gmail.com>
+
+        * inst/include/Rcpp/sugar/functions/strings/trimws.h: Added sugar
+        function trimws with unit tests
+        * inst/include/Rcpp/sugar/functions/strings/strings.h: Idem
+        * inst/unitTests/cpp/sugar.cpp: Idem
+        * inst/unitTests/runit.sugar.R: Idem
+
 2017-04-20  Dirk Eddelbuettel  <edd@debian.org>
 
         * DESCRIPTION (Version, Date): Roll minor version

inst/NEWS.Rd

@@ -25,6 +25,11 @@
       (James Balamuta in \ghpr{661} addressing \ghit{628}, \ghit{563},
       \ghit{552}, \ghit{460}, \ghit{419}, and \ghit{251}).
     }
+    \item Changes in Rcpp Sugar:
+    \itemize{
+      \item Added sugar function \code{trimws} (Nathan Russell in \ghpr{680}
+      addressing \ghit{679}).
+    }
   }
 }
 

inst/include/Rcpp/sugar/functions/strings/strings.h

@@ -23,5 +23,6 @@
 #define RCPP_SUGAR_FUNCTIONS_STRINGS_H
 
 #include <Rcpp/sugar/functions/strings/collapse.h>
+#include <Rcpp/sugar/functions/strings/trimws.h>
 
 #endif

inst/include/Rcpp/sugar/functions/strings/trimws.h

@@ -0,0 +1,219 @@
+// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; indent-tabs-mode: nil; -*-
+//
+// trimws.h: Rcpp R/C++ interface class library -- trimws
+//
+// Copyright (C) 2017 Nathan Russell
+//
+// This file is part of Rcpp.
+//
+// Rcpp is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 2 of the License, or
+// (at your option) any later version.
+//
+// Rcpp is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef Rcpp__sugar__trimws_h
+#define Rcpp__sugar__trimws_h
+
+#include <string>
+#include <cstring>
+
+namespace Rcpp {
+namespace sugar {
+namespace detail {
+
+
+/*  NB: std::isspace is not used because it also counts
+    '\f' and '\v' as whitespace, whereas base::trimws only
+    checks for ' ', '\t', '\r', and '\n'  */
+inline bool isws(const char c) {
+    return c == ' ' || c == '\t' || c == '\n' || c == '\r';
+}
+
+inline const char* trim_left(const char* str) {
+    if (!str) {
+        return "";
+    }
+
+    while (isws(*str)) {
+        ++str;
+    }
+
+    return str;
+}
+
+inline const char* trim_right(const char* str, R_len_t sz, std::string* buff) {
+    if (!str) {
+        return "";
+    }
+
+    buff->clear();
+    const char* ptr = str + sz - 1;
+
+    for (; ptr > str && isws(*ptr); --sz, --ptr);
+
+    buff->append(str, sz - isws(*ptr));
+    return buff->c_str();
+}
+
+inline const char* trim_both(const char* str, R_len_t sz, std::string* buff) {
+    if (!str) {
+        return "";
+    }
+
+    buff->clear();
+
+    while (isws(*str)) {
+        ++str; --sz;
+    }
+
+    const char* ptr = str + sz - 1;
+
+    for (; ptr > str && isws(*ptr); --sz, --ptr);
+
+    buff->append(str, sz);
+    return buff->c_str();
+}
+
+
+} // detail
+} // sugar
+
+
+inline Vector<STRSXP> trimws(const Vector<STRSXP>& x, const char* which = "both") {
+    R_xlen_t i = 0, sz = x.size();
+    Vector<STRSXP> res = no_init(sz);
+    std::string buffer;
+
+    if (*which == 'b') {
+        for (; i < sz; i++) {
+            if (traits::is_na<STRSXP>(x[i])) {
+                res[i] = x[i];
+            } else {
+                res[i] = sugar::detail::trim_both(
+                    x[i],
+                    LENGTH(x[i]),
+                    &buffer
+                );
+            }
+        }
+    } else if (*which == 'l') {
+        for (; i < sz; i++) {
+            if (traits::is_na<STRSXP>(x[i])) {
+                res[i] = x[i];
+            } else {
+                res[i] = sugar::detail::trim_left(x[i]);
+            }
+        }
+    } else if (*which == 'r') {
+        for (; i < sz; i++) {
+            if (traits::is_na<STRSXP>(x[i])) {
+                res[i] = x[i];
+            } else {
+                res[i] = sugar::detail::trim_right(
+                    x[i],
+                    LENGTH(x[i]),
+                    &buffer
+                );
+            }
+        }
+    } else {
+        stop("Invalid `which` argument '%s'!", which);
+        return Vector<STRSXP>::create("Unreachable");
+    }
+
+    return res;
+}
+
+inline Matrix<STRSXP> trimws(const Matrix<STRSXP>& x, const char* which = "both") {
+    R_xlen_t i = 0, nr = x.nrow(), nc = x.ncol(), sz = x.size();
+    Matrix<STRSXP> res = no_init(nr, nc);
+    std::string buffer;
+
+    if (*which == 'b') {
+        for (; i < sz; i++) {
+            if (traits::is_na<STRSXP>(x[i])) {
+                res[i] = x[i];
+            } else {
+                res[i] = sugar::detail::trim_both(
+                    x[i],
+                    LENGTH(x[i]),
+                    &buffer
+                );
+            }
+        }
+    } else if (*which == 'l') {
+        for (; i < sz; i++) {
+            if (traits::is_na<STRSXP>(x[i])) {
+                res[i] = x[i];
+            } else {
+                res[i] = sugar::detail::trim_left(x[i]);
+            }
+        }
+    } else if (*which == 'r') {
+        for (; i < sz; i++) {
+            if (traits::is_na<STRSXP>(x[i])) {
+                res[i] = x[i];
+            } else {
+                res[i] = sugar::detail::trim_right(
+                    x[i],
+                    LENGTH(x[i]),
+                    &buffer
+                );
+            }
+        }
+    } else {
+        stop("Invalid `which` argument '%s'!", which);
+        return Matrix<STRSXP>();
+    }
+
+    return res;
+}
+
+inline String trimws(const String& str, const char* which = "both") {
+    std::string buffer;
+
+    if (*which == 'b') {
+        if (traits::is_na<STRSXP>(str.get_sexp())) {
+            return String(str.get_sexp());
+        }
+        return sugar::detail::trim_both(
+            str.get_cstring(),
+            LENGTH(str.get_sexp()),
+            &buffer
+        );
+    }
+
+    if (*which == 'l') {
+        if (traits::is_na<STRSXP>(str.get_sexp())) {
+            return String(str.get_sexp());
+        }
+        return sugar::detail::trim_left(str.get_cstring());
+    }
+
+    if (*which == 'r') {
+        if (traits::is_na<STRSXP>(str.get_sexp())) {
+            return String(str.get_sexp());
+        }
+        return sugar::detail::trim_right(
+            str.get_cstring(),
+            LENGTH(str.get_sexp()),
+            &buffer
+        );
+    }
+
+    stop("Invalid `which` argument '%s'!", which);
+    return String("Unreachable");
+}
+
+
+} // Rcpp
+
+#endif // Rcpp__sugar__trimws_h

inst/unitTests/cpp/sugar.cpp

@@ -1201,3 +1201,21 @@ LogicalMatrix UpperTri(NumericMatrix x, bool diag = false) {
 LogicalMatrix LowerTri(NumericMatrix x, bool diag = false) {
     return lower_tri(x, diag);
 }
+
+
+// 22 April 2017: trimws
+
+// [[Rcpp::export]]
+CharacterVector vtrimws(CharacterVector x, const char* which = "both") {
+    return trimws(x, which);
+}
+
+// [[Rcpp::export]]
+CharacterMatrix mtrimws(CharacterMatrix x, const char* which = "both") {
+    return trimws(x, which);
+}
+
+// [[Rcpp::export]]
+String strimws(String x, const char* which = "both") {
+    return trimws(x, which);
+}