Merge pull request #13 from p-ranav/feature/9

Feature/9

README.md

@@ -2,6 +2,20 @@
   <img height="75" src="img/logo.png" alt="csv2"/>
 </p>
 
+## Table of Contents
+
+*    [CSV Reader](#csv-reader)
+     *    [Performance Benchmark](#performance-benchmark)
+     *    [Reader API](#reader-api)
+*    [CSV Writer](#csv-writer)
+     *    [Writer API](#writer-api)
+*    [Compiling Tests](#compiling-tests)
+*    [Generating Single Header](#generating-single-header)
+*    [Contributing](#contributing)
+*    [License](#license)
+
+## CSV Reader
+
 ```cpp
 #include <csv2/reader.hpp>
 
@@ -24,7 +38,7 @@ int main() {
 }
 ```
 
-## Performance Benchmark
+### Performance Benchmark
 
 This benchmark measures the average execution time (of 5 runs after 3 warmup runs) for `csv2` to memory-map the input CSV file and iterate over every cell in the CSV. See `benchmark/main.cpp` for more details.
 
@@ -34,7 +48,7 @@ g++ -I../include -O3 -std=c++11 -o main main.cpp
 ./main <csv_file>
 ```
 
-### Hardware 
+#### Hardware 
 
 ```
 MacBook Pro (15-inch, 2019)
@@ -43,7 +57,7 @@ Memory: 32 GB 2400 MHz DDR4
 Operating System: macOS Catalina version 10.15.3
 ```
 
-### Results (as of 23 APR 2020)
+#### Results (as of 23 APR 2020)
 
 | Dataset | File Size | Rows | Cols | Time |
 |:---     |       ---:|  ---:|  ---:|  ---:|
@@ -59,7 +73,7 @@ Operating System: macOS Catalina version 10.15.3
 | [SHA-1 password hash dump](https://www.kaggle.com/urvishramaiya/have-i-been-pwnd) | 11 GB | 2,62,974,241 | 2 | 19.505s |
 | [DOHUI NOH scaled_data](https://www.kaggle.com/seaa0612/scaled-data) | 16 GB | 496,782 | 3213 | 32.780s |
 
-## API
+### Reader API
 
 Here is the public API available to you:
 
@@ -123,6 +137,51 @@ public:
 };
 ```
 
+## CSV Writer
+
+This library also provides a basic `csv2::Writer` class - one that can be used to write CSV rows to file. Here's a basic usage:
+
+```cpp
+#include <csv2/writer.hpp>
+#include <vector>
+#include <string>
+using namespace csv2;
+
+int main() {
+    std::ofstream stream("foo.csv");
+    Writer<delimiter<','>> writer(stream);
+
+    std::vector<std::vector<std::string>> rows = 
+        {
+            {"a", "b", "c"},
+            {"1", "2", "3"},
+            {"4", "5", "6"}
+        };
+
+    writer.write_rows(rows);
+    stream.close();
+}
+```
+
+### Writer API
+
+Here is the public API available to you:
+
+```cpp
+template <class delimiter = delimiter<','>>
+class Writer {
+public:
+
+  // Construct using an std::ofstream
+  Writer(output_file_stream stream);
+
+  // Use this to write a single row to file
+  void write_row(container_of_strings row);
+
+  // Use this to write a list of rows to file
+  void write_rows(container_of_rows rows);
+```
+
 ## Compiling Tests
 
 ```bash
@@ -133,6 +192,12 @@ cd test
 ./csv2_test
 ```
 
+## Generating Single Header
+
+```bash
+python3 utils/amalgamate/amalgamate.py -c single_include.json -s .
+```
+
 ## Contributing
 Contributions are welcome, have a look at the [CONTRIBUTING.md](CONTRIBUTING.md) document for more information.
 

include/csv2/mio.hpp

@@ -1,3 +1,4 @@
+
 /* Copyright 2017 https://github.com/mandreyel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of this

include/csv2/parameters.hpp

@@ -0,0 +1,50 @@
+
+#pragma once
+#include <utility>
+
+namespace csv2 {
+
+namespace trim_policy {
+struct no_trimming {
+public:
+  static std::pair<size_t, size_t> trim(const char *buffer, size_t start, size_t end) {
+    (void)(buffer); // to silence unused parameter warning
+    return {start, end};
+  }
+};
+
+template <char... character_list> struct trim_characters {
+private:
+  constexpr static bool is_trim_char(char) { return false; }
+
+  template <class... Tail> constexpr static bool is_trim_char(char c, char head, Tail... tail) {
+    return c == head || is_trim_char(c, tail...);
+  }
+
+public:
+  static std::pair<size_t, size_t> trim(const char *buffer, size_t start, size_t end) {
+    size_t new_start = start, new_end = end;
+    while (new_start != new_end && is_trim_char(buffer[new_start], character_list...))
+      ++new_start;
+    while (new_start != new_end && is_trim_char(buffer[new_end - 1], character_list...))
+      --new_end;
+    return {new_start, new_end};
+  }
+};
+
+using trim_whitespace = trim_characters<' ', '\t'>;
+} // namespace trim_policy
+
+template <char character> struct delimiter {
+  constexpr static char value = character;
+};
+
+template <char character> struct quote_character {
+  constexpr static char value = character;
+};
+
+template <bool flag> struct first_row_is_header {
+  constexpr static bool value = flag;
+};
+
+}

include/csv2/reader.hpp

@@ -1,55 +1,13 @@
+
 #pragma once
 #include <cstring>
 #include <csv2/mio.hpp>
+#include <csv2/parameters.hpp>
 #include <istream>
 #include <string>
-#include <utility>
 
 namespace csv2 {
 
-namespace trim_policy {
-struct no_trimming {
-public:
-  static std::pair<size_t, size_t> trim(const char *buffer, size_t start, size_t end) {
-    (void)(buffer); // to silence unused parameter warning
-    return {start, end};
-  }
-};
-
-template <char... character_list> struct trim_characters {
-private:
-  constexpr static bool is_trim_char(char) { return false; }
-
-  template <class... Tail> constexpr static bool is_trim_char(char c, char head, Tail... tail) {
-    return c == head || is_trim_char(c, tail...);
-  }
-
-public:
-  static std::pair<size_t, size_t> trim(const char *buffer, size_t start, size_t end) {
-    size_t new_start = start, new_end = end;
-    while (new_start != new_end && is_trim_char(buffer[new_start], character_list...))
-      ++new_start;
-    while (new_start != new_end && is_trim_char(buffer[new_end - 1], character_list...))
-      --new_end;
-    return {new_start, new_end};
-  }
-};
-
-using trim_whitespace = trim_characters<' ', '\t'>;
-} // namespace trim_policy
-
-template <char character> struct delimiter {
-  constexpr static char value = character;
-};
-
-template <char character> struct quote_character {
-  constexpr static char value = character;
-};
-
-template <bool flag> struct first_row_is_header {
-  constexpr static bool value = flag;
-};
-
 template <class delimiter = delimiter<','>, class quote_character = quote_character<'"'>,
           class first_row_is_header = first_row_is_header<true>,
           class trim_policy = trim_policy::trim_whitespace>

include/csv2/writer.hpp

@@ -0,0 +1,41 @@
+
+#pragma once
+#include <cstring>
+#include <csv2/parameters.hpp>
+#include <fstream>
+#include <string>
+#include <utility>
+#include <iostream>
+
+namespace csv2 {
+
+template <class delimiter = delimiter<','>>
+class Writer {
+    std::ofstream& stream_;    // output stream for the writer
+public:
+    template <typename Stream>
+    Writer(Stream&& stream) : stream_(std::forward<Stream>(stream)) {}
+
+    ~Writer() {
+        stream_.close();
+    }
+
+    template <typename Container>
+    void write_row(Container&& row) {
+        const auto& strings = std::forward<Container>(row);
+        const auto delimiter_string = std::string(1, delimiter::value);
+        std::copy(strings.begin(), strings.end() - 1,
+            std::ostream_iterator<std::string>(stream_, delimiter_string.c_str()));
+        stream_ << strings.back() << "\n";
+    }
+
+    template <typename Container>
+    void write_rows(Container&& rows) {
+        const auto& container_of_rows = std::forward<Container>(rows);
+        for (const auto& row : container_of_rows) {
+            write_row(row);
+        }
+    }
+};
+
+}

single_include.json

@@ -0,0 +1,11 @@
+{
+    "project": "CSV for Modern C++",
+    "target": "single_include/csv2/csv2.hpp",
+    "sources": [
+        "include/csv2/mio.hpp",
+        "include/csv2/parameters.hpp",
+        "include/csv2/reader.hpp",
+        "include/csv2/writer.hpp"
+    ],
+    "include_paths": ["include"]
+}