* Export the nix-env derivation name parsing and version comparison

  logic through the `parseDrvName' and `compareVersions' primops.
  This will allow expressions to easily check whether some dependency
  is a specific needed version or falls in some version range.  See
  tests/lang/eval-okay-versions.nix for examples.

1 files changed, 105 insertions, 0 deletions

diff --git a/src/libexpr/names.cc b/src/libexpr/names.cc
new file mode 100644
index 000000000000..29c7ddb4d70f
--- /dev/null
+++ b/src/libexpr/names.cc
@@ -0,0 +1,105 @@
+#include "names.hh"
+#include "util.hh"
+
+
+namespace nix {
+
+
+DrvName::DrvName()
+{
+    name = "";
+}
+
+
+/* Parse a derivation name.  The `name' part of a derivation name is
+   everything up to but not including the first dash *not* followed by
+   a letter.  The `version' part is the rest (excluding the separating
+   dash).  E.g., `apache-httpd-2.0.48' is parsed to (`apache-httpd',
+   '2.0.48'). */
+DrvName::DrvName(const string & s) : hits(0)
+{
+    name = fullName = s;
+    for (unsigned int i = 0; i < s.size(); ++i) {
+        /* !!! isalpha/isdigit are affected by the locale. */
+        if (s[i] == '-' && i + 1 < s.size() && !isalpha(s[i + 1])) {
+            name = string(s, 0, i);
+            version = string(s, i + 1);
+            break;
+        }
+    }
+}
+
+
+bool DrvName::matches(DrvName & n)
+{
+    if (name != "*" && name != n.name) return false;
+    if (version != "" && version != n.version) return false;
+    return true;
+}
+
+
+static string nextComponent(string::const_iterator & p,
+    const string::const_iterator end)
+{
+    /* Skip any dots and dashes (component separators). */
+    while (p != end && (*p == '.' || *p == '-')) ++p;
+
+    if (p == end) return "";
+
+    /* If the first character is a digit, consume the longest sequence
+       of digits.  Otherwise, consume the longest sequence of
+       non-digit, non-separator characters. */
+    string s;
+    if (isdigit(*p))
+        while (p != end && isdigit(*p)) s += *p++;
+    else
+        while (p != end && (!isdigit(*p) && *p != '.' && *p != '-'))
+            s += *p++;
+    
+    return s;
+}
+
+
+static bool componentsLT(const string & c1, const string & c2)
+{
+    int n1, n2;
+    bool c1Num = string2Int(c1, n1), c2Num = string2Int(c2, n2);
+
+    if (c1Num && c2Num) return n1 < n2;
+    else if (c1 == "" && c2Num) return true;
+    else if (c1 == "pre" && c2 != "pre") return true;
+    else if (c2 == "pre") return false;
+    /* Assume that `2.3a' < `2.3.1'. */
+    else if (c2Num) return true;
+    else if (c1Num) return false;
+    else return c1 < c2;
+}
+
+
+int compareVersions(const string & v1, const string & v2)
+{
+    string::const_iterator p1 = v1.begin();
+    string::const_iterator p2 = v2.begin();
+    
+    while (p1 != v1.end() || p2 != v2.end()) {
+        string c1 = nextComponent(p1, v1.end());
+        string c2 = nextComponent(p2, v2.end());
+        if (componentsLT(c1, c2)) return -1;
+        else if (componentsLT(c2, c1)) return 1;
+    }
+
+    return 0;
+}
+
+
+DrvNames drvNamesFromArgs(const Strings & opArgs)
+{
+    DrvNames result;
+    for (Strings::const_iterator i = opArgs.begin();
+         i != opArgs.end(); ++i)
+        result.push_back(DrvName(*i));
+    return result;
+}
+
+ 
+}