add validate function (#1)

* add validate function

* apply fixes

* add include variant

Author: anonrig

.gitignore

@@ -0,0 +1,2 @@
+build
+cmake-build-debug

include/version_weaver.h

@@ -1,16 +1,60 @@
 #ifndef VERSION_WEAVER_H
 #define VERSION_WEAVER_H
+#include <optional>
 #include <string_view>
 #include <string>
+#include <variant>
 
 namespace version_weaver {
+
+  // https://semver.org/#does-semver-have-a-size-limit-on-the-version-string
+  static constexpr size_t MAX_VERSION_LENGTH = 256;
+
   bool validate(std::string_view version);
   bool gt(std::string_view version1, std::string_view version2);
   bool lt(std::string_view version1, std::string_view version2);
   bool satisfies(std::string_view version, std::string_view range);
   std::string coerce(std::string_view version);
   std::string minimum(std::string_view range);
   std::string clean(std::string_view range);
+
+  // A normal version number MUST take the form X.Y.Z where X, Y, and Z are
+  // non-negative integers, and MUST NOT contain leading zeroes.
+  // X is the major version, Y is the minor version, and Z is the patch version.
+  // Each element MUST increase numerically.
+  // For instance: 1.9.0 -> 1.10.0 -> 1.11.0.
+  struct Version {
+
+    std::string_view major;
+    std::string_view minor;
+    std::string_view patch;
+
+    // A pre-release version MAY be denoted by appending a hyphen and a series
+    // of dot separated identifiers immediately following the patch version.
+    // - Identifiers MUST comprise only ASCII alphanumerics and hyphens [0-9A-Za-z-].
+    // - Identifiers MUST NOT be empty.
+    // - Numeric identifiers MUST NOT include leading zeroes.
+    //
+    // Examples: 1.0.0-alpha, 1.0.0-alpha.1, 1.0.0-0.3.7, 1.0.0-x.7.z.92, 1.0.0-x-y-z.--.
+    std::optional<std::string_view> pre_release;
+
+    // Build metadata MAY be denoted by appending a plus sign and a series of dot
+    // separated identifiers immediately following the patch or pre-release version.
+    // - Identifiers MUST comprise only ASCII alphanumerics and hyphens [0-9A-Za-z-].
+    // - Identifiers MUST NOT be empty.
+    // Build metadata MUST be ignored when determining version precedence.
+    // Thus two versions that differ only in the build metadata, have the same precedence.
+    //
+    // Examples: 1.0.0-alpha+001, 1.0.0+20130313144700, 1.0.0-beta+exp.sha.5114f85, 1.0.0+21AF26D3----117B344092BD.
+    std::optional<std::string_view> build;
+  };
+
+  enum ParseError {
+    VERSION_LARGER_THAN_MAX_LENGTH,
+    INVALID_INPUT,
+  };
+
+  std::variant<Version, ParseError> parse(std::string_view version);
 }
 
 #endif // VERSION_WEAVER_H

src/version_weaver.cpp

@@ -1,10 +1,76 @@
 #include "version_weaver.h"
 namespace version_weaver {
-  bool validate(std::string_view version) { return true; }
+  bool validate(std::string_view version) {
+    return std::holds_alternative<Version>(parse(version));
+  }
+
   bool gt(std::string_view version1, std::string_view version2)  { return true; }
   bool lt(std::string_view version1, std::string_view version2) { return true; }
   bool satisfies(std::string_view version, std::string_view range) { return true; }
   std::string coerce(std::string_view version)  { return ""; }
   std::string minimum(std::string_view range)  { return ""; }
   std::string clean(std::string_view range)  { return ""; }
+
+  std::variant<Version, ParseError> parse(std::string_view input) {
+    if (input.size() > MAX_VERSION_LENGTH) {
+      return ParseError::VERSION_LARGER_THAN_MAX_LENGTH;
+    }
+
+    std::string_view input_copy = input;
+    // TODO: Trim leading and trailing whitespace
+
+    auto dot_iterator = input_copy.find('.');
+    if (dot_iterator == std::string_view::npos) {
+      // Only major exists. No minor or patch.
+      return ParseError::INVALID_INPUT;
+    }
+    Version version;
+    auto major = input_copy.substr(0, dot_iterator);
+
+    if (major.empty() || major.front() == '0') {
+      // Version components can not have leading zeroes.
+      return ParseError::INVALID_INPUT;
+    }
+    version.major = major;
+    input_copy = input_copy.substr(dot_iterator + 1);
+    dot_iterator = input_copy.find('.');
+    if (dot_iterator == std::string_view::npos) {
+      // Only major and minor exists. No patch.
+      return ParseError::INVALID_INPUT;
+    }
+
+    auto minor = input_copy.substr(0, dot_iterator);
+    if (minor.empty() || minor.front() == '0') {
+      // Version components can not have leading zeroes.
+      return ParseError::INVALID_INPUT;
+    }
+    version.minor = minor;
+    input_copy = input_copy.substr(dot_iterator + 1);
+    dot_iterator = input_copy.find('.');
+    if (dot_iterator == std::string_view::npos) {
+      // Only major, minor and patch exists.
+      return ParseError::INVALID_INPUT;
+    }
+
+    auto patch = input_copy.substr(0, dot_iterator);
+    if (patch.empty() || patch.front() == '0') {
+      // Version components can not have leading zeroes.
+      return ParseError::INVALID_INPUT;
+    }
+    version.patch = patch;
+    input_copy = input_copy.substr(dot_iterator + 1);
+
+    auto pre_release_iterator = input_copy.find('-');
+    if (pre_release_iterator != std::string_view::npos) {
+      version.pre_release = input_copy.substr(0, pre_release_iterator);
+      input_copy = input_copy.substr(pre_release_iterator + 1);
+      if (input_copy.find('.') != std::string_view::npos) {
+        // Build metadata exists.
+        auto build_iterator = input_copy.find('.');
+        version.build = input_copy.substr(0, build_iterator);
+      }
+    }
+
+    return version;
+  }
 }