shell: provide parser with expr_or_range() function

shell/d.cpp

@@ -75,8 +75,17 @@ static uint32_t parse_d(Session &session, Parser &parser)
         return 0;
     uint32_t address = session.current_space->cursor;
 
-    if(!parser.at_end())
-        address = parser.expr(session.current_space);
+    if(!parser.at_end()) {
+        auto v = parser.expr_or_range(session.current_space);
+
+        if(std::holds_alternative<long>(v)) {
+            address = std::get<long>(v);
+        }
+        else {
+            // TODO: Use an args struct etc. This is placeholder.
+            address = std::get<Range>(v).start;
+        }
+    }
 
     parser.end();
     return address;

shell/parser.cpp

@@ -142,24 +142,7 @@ void Parser::dump_command()
 {
     while(!at_end()) {
         Token t = m_la;
-
-        if(t.type == T::NUM)
-            fmt::print("NUM {:#x}\n", t.value.NUM);
-        else if(t.type == T::SYSCALL)
-            fmt::print("SYSCALL %{:04x}\n", t.value.NUM);
-        else if(t.type == T::SYMBOL)
-            fmt::print("SYMBOL '{}'\n", t.value.STRING);
-        else if(t.type == T::OPTION)
-            fmt::print("OPTION '{}'\n", t.value.STRING);
-        else if(t.type == T::STRING)
-            fmt::print("STRING '{}'\n", t.value.STRING);
-        else if(t.type == '>')
-            fmt::print(">>\n");
-        else if(t.type == '<')
-            fmt::print("<<\n");
-        else
-            fmt::print("{}\n", (char)t.type);
-
+        fmt::print("{}\n", t.str());
         feed();
     }
 }
@@ -246,7 +229,7 @@ Range Parser::range(VirtualSpace *space, long before, long after)
 {
     long start = expr(space);
 
-    /* Accept non-rangs if (before) and (after) are provided */
+    /* Accept non-ranges if (before) and (after) are provided */
     if(m_la.type != ':' && m_la.type != '.' && before >= 0 && after >= 0)
         return {start - before, start + after};
 
@@ -259,6 +242,25 @@ Range Parser::range(VirtualSpace *space, long before, long after)
     return r;
 }
 
+std::variant<long, Range> Parser::expr_or_range(VirtualSpace *space)
+{
+    long start = expr(space);
+
+    if(m_la.type == ':') {
+        expect(':');
+        long length = expr(space);
+        return (Range){start, start + length};
+    }
+    else if(m_la.type == '.') {
+        expect('.');
+        long end = expr(space);
+        return (Range){start, end};
+    }
+    else {
+        return (long)start;
+    }
+}
+
 FxOS::MemoryRegion Parser::region(VirtualSpace *space, long before, long after)
 {
     if(m_la.type == '$' || m_la.type == '(' || m_la.type == '-'

shell/parser.h

@@ -12,6 +12,7 @@
 #include <vector>
 #include <map>
 #include <functional>
+#include <variant>
 
 #include <fxos/memory.h>
 #include <fxos/vspace.h>
@@ -144,8 +145,10 @@ public:
 	long expr(VirtualSpace *space);
 	/* Read a range; again $ and symbols are interpreted. If (before) and
 	   (after) are both specified, a single value will also be accepted, and
-	   the range [value+before, value.after) will be returned. */
+	   the range [value-before, value+after) will be returned. */
 	Range range(VirtualSpace *space, long before=-1, long after=-1);
+	/* Read an expression or a range */
+	std::variant<long, Range> expr_or_range(VirtualSpace *space);
 	/* Read a memory region (allows both ranges and symbolic names) */
 	FxOS::MemoryRegion region(VirtualSpace *space, long before=-1,
 		long after=-1);