Only do "effective escaping" (['"\$(]) on the command line

This will make things more convenient on Windows provided we use "sane"
paths (no spaces, no (), etc).

6 files changed, 57 insertions, 24 deletions

diff --git a/build2/b.cli b/build2/b.cli
index 013a756..f0cd48e 100644
--- a/build2/b.cli
+++ b/build2/b.cli
@@ -178,6 +178,21 @@ namespace build2
        config.install.root=/usr/local config.install.root.sudo=sudo \
        configure
      \
+
+     Note also that buildspec and command line variable values are treated as
+     \cb{buildfile} fragments and so can use quoting and escaping as well as
+     contain variable expansions and evaluation contexts. However, to be more
+     usable on various platforms, escaping in these two situations is limited
+     to the \i{effective sequences} of \cb{\\'}, \cb{\\\"}, \cb{\\\\},
+     \cb{\\$}, and \cb{\\(} with all other sequences interpreted as is.
+     Together with double-quoting this is sufficient to represent any value.
+     For example:
+
+     \
+     b config.install.root=c:\projects\install
+     b \"config.install.root='c:\Program Files (x86)\test\'\"
+     b 'config.cxx.poptions=-DFOO_STR=\"foo\"'
+     \
      "
   }
 
diff --git a/build2/b.cxx b/build2/b.cxx
index 748eda7..b2ba2c1 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -30,8 +30,6 @@
 #include <build2/context>
 #include <build2/variable>
 
-#include <build2/token>
-#include <build2/lexer>
 #include <build2/parser>
 
 #include <build2/b-options>
diff --git a/build2/context.cxx b/build2/context.cxx
index e08fb52..f756bfc 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -97,7 +97,12 @@ namespace build2
     {
       istringstream is (s);
       is.exceptions (istringstream::failbit | istringstream::badbit);
-      lexer l (is, path ("<cmdline>"));
+
+      // Similar to buildspec we do "effective escaping" and only for ['"\$(]
+      // (basically what's necessary inside a double-quoted literal plus the
+      // single quote).
+      //
+      lexer l (is, path ("<cmdline>"), "\'\"\\$(");
 
       // The first token should be a name, either the variable name or the
       // scope qualification.
@@ -143,7 +148,7 @@ namespace build2
       if (c == '!' && !dir.empty ())
         fail << "scope-qualified global override of variable " << n;
 
-      variable_visibility v (c == '/' ? variable_visibility::scope :
+      variable_visibility v (c == '/' ? variable_visibility::scope   :
                              c == '%' ? variable_visibility::project :
                              variable_visibility::normal);
 
diff --git a/build2/lexer b/build2/lexer
index c856344..42222e6 100644
--- a/build2/lexer
+++ b/build2/lexer
@@ -37,10 +37,19 @@ namespace build2
   class lexer: protected butl::char_scanner
   {
   public:
+    // If escape is not NULL then only escape sequences with characters from
+    // this string are considered "effective escapes" with all others passed
+    // through as is. Note that the escape string is not copied.
+    //
     lexer (istream& is,
            const path& name,
+           const char* escapes = nullptr,
            void (*processor) (token&, const lexer&) = nullptr)
-        : char_scanner (is), fail (name), processor_ (processor), sep_ (false)
+        : char_scanner (is),
+          fail (name),
+          escapes_ (escapes),
+          processor_ (processor),
+          sep_ (false)
     {
       mode (lexer_mode::normal);
     }
@@ -100,9 +109,6 @@ namespace build2
     bool
     skip_spaces ();
 
-    xchar
-    escape ();
-
     // Diagnostics.
     //
   private:
@@ -120,8 +126,10 @@ namespace build2
   private:
     fail_mark fail;
 
+    const char* escapes_;
     void (*processor_) (token&, const lexer&);
 
+
     struct state
     {
       lexer_mode mode;
diff --git a/build2/lexer.cxx b/build2/lexer.cxx
index 773cd88..84e972e 100644
--- a/build2/lexer.cxx
+++ b/build2/lexer.cxx
@@ -4,6 +4,8 @@
 
 #include <build2/lexer>
 
+#include <cstring> // strchr()
+
 using namespace std;
 
 namespace build2
@@ -309,10 +311,23 @@ namespace build2
       if (c == '\\')
       {
         get ();
-        c = escape ();
-        if (c != '\n') // Ignore.
-          lexeme += c;
-        continue;
+        xchar e (peek ());
+
+        if (escapes_ == nullptr ||
+            (!eos (e) && strchr (escapes_, e) != nullptr))
+        {
+          get ();
+
+          if (eos (e))
+            fail (e) << "unterminated escape sequence";
+
+          if (e != '\n') // Ignore.
+            lexeme += e;
+
+          continue;
+        }
+        else
+          unget (c); // Treat as a normal character.
       }
 
       // If we are quoted, these are ordinary characters.
@@ -484,17 +499,6 @@ namespace build2
     return r;
   }
 
-  lexer::xchar lexer::
-  escape ()
-  {
-    xchar c (get ());
-
-    if (eos (c))
-      fail (c) << "unterminated escape sequence";
-
-    return c;
-  }
-
   location_prologue lexer::fail_mark_base::
   operator() (const xchar& c) const
   {
diff --git a/build2/parser.cxx b/build2/parser.cxx
index 99e4227..a64a94e 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -2680,7 +2680,10 @@ namespace build2
   {
     path_ = &name;
 
-    lexer l (is, *path_, &paren_processor);
+    // We do "effective escaping" and only for ['"\$(] (basically what's
+    // necessary inside a double-quoted literal plus the single quote).
+    //
+    lexer l (is, *path_, "\'\"\\$(", &paren_processor);
     lexer_ = &l;
     target_ = nullptr;
     scope_ = root_ = global_scope;