Add support for unit switch &parse-at and &parse-from attributes.

Closes #913.
zeek · May 28, 2021 · 57f2e12 · 57f2e12
1 parent 9ffdf6a
commit 57f2e12
Show file tree

Hide file tree

Showing 4 changed files with 67 additions and 2 deletions.
diff --git a/spicy/toolchain/src/compiler/codegen/parser-builder.cc b/spicy/toolchain/src/compiler/codegen/parser-builder.cc
@@ -981,8 +981,39 @@ struct ProductionVisitor
     void operator()(const production::Switch& p) {
         builder()->addCall("hilti::debugIndent", {builder::string("spicy")});
 
+        if ( const auto& a = AttributeSet::find(p.attributes(), "&parse-from") ) {
+            // Redirect input to a bytes value.
+            auto pstate = state();
+            pstate.trim = builder::bool_(false);
+            pstate.lahead = builder()->addTmp("parse_lah", look_ahead::Type, look_ahead::None);
+            pstate.lahead_end = builder()->addTmp("parse_lahe", type::stream::Iterator());
+            auto expr = a->valueAs<Expression>();
+
+            auto tmp = builder()->addTmp("parse_from", type::ValueReference(type::Stream()), *expr);
+            pstate.data = tmp;
+            pstate.cur = builder()->addTmp("parse_cur", type::stream::View(), builder::deref(tmp));
+            pstate.ncur = {};
+            builder()->addMemberCall(tmp, "freeze", {});
+
+            pushState(std::move(pstate));
+        }
+
+        if ( auto a = AttributeSet::find(p.attributes(), "&parse-at") ) {
+            // Redirect input to a stream position.
+            auto pstate = state();
+            pstate.trim = builder::bool_(false);
+            pstate.lahead = builder()->addTmp("parse_lah", look_ahead::Type, look_ahead::None);
+            pstate.lahead_end = builder()->addTmp("parse_lahe", type::stream::Iterator());
+            auto expr = a->valueAs<Expression>();
+
+            auto cur = builder::memberCall(state().cur, "advance", {*expr});
+            pstate.cur = builder()->addTmp("parse_cur", cur);
+            pstate.ncur = {};
+            pushState(std::move(pstate));
+        }
+
         std::optional<Expression> ncur;
-        if ( auto a = AttributeSet::find(p.attributes(), "&size") ) {
+        if ( const auto& a = AttributeSet::find(p.attributes(), "&size") ) {
             // Limit input to the specified length.
             auto length = builder::coerceTo(*a->valueAs<Expression>(), type::UnsignedInteger(64));
             auto limited = builder()->addTmp("limited", builder::memberCall(state().cur, "limit", {length}));
@@ -1023,6 +1054,9 @@ struct ProductionVisitor
             builder()->addAssign(state().cur, *ncur);
         }
 
+        if ( AttributeSet::find(p.attributes(), "&parse-from") || AttributeSet::find(p.attributes(), "&parse-at") )
+            popState();
+
         builder()->addCall("hilti::debugDedent", {builder::string("spicy")});
     }
 

diff --git a/spicy/toolchain/src/compiler/visitors/validator.cc b/spicy/toolchain/src/compiler/visitors/validator.cc
@@ -651,7 +651,7 @@ struct PreTransformVisitor : public hilti::visitor::PreOrder<void, PreTransformV
             for ( const auto& attr : attrs->attributes() ) {
                 const auto& tag = attr.tag();
 
-                if ( tag != "&size" )
+                if ( tag != "&size" && tag != "&parse-at" && tag != "&parse-from" )
                     error(fmt("attribute '%s' is not supported here", tag), p);
             }
         }

diff --git a/tests/Baseline/spicy.types.unit.switch-parse-from/output b/tests/Baseline/spicy.types.unit.switch-parse-from/output
@@ -0,0 +1,9 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Mini::X {
+  a: \x01
+  b: \x01
+}
+Mini::Y {
+  a: \x01
+  b: \x01\x02\x03
+}
diff --git a/tests/spicy/types/unit/switch-parse-from.spicy b/tests/spicy/types/unit/switch-parse-from.spicy
@@ -0,0 +1,22 @@
+# @TEST-EXEC: ${SPICYC} %INPUT -j -o %INPUT.hlto
+# @TEST-EXEC: ${SCRIPTS}/printf '\01\02\03' | spicy-dump -p Mini::X %INPUT.hlto >>output
+# @TEST-EXEC: ${SCRIPTS}/printf '\01\02\03' | spicy-dump -p Mini::Y %INPUT.hlto >>output
+# @TEST-EXEC: btest-diff output
+
+module Mini;
+
+public type X = unit {
+    a: bytes &size=1;
+    switch ( self.a ) {
+        * -> b: bytes &eod;
+    } &parse-from=self.a;
+};
+
+public type Y = unit {
+    %random-access;
+
+    a: bytes &size=1;
+    switch ( self.a ) {
+        * -> b: bytes &eod;
+    } &parse-at=self.input();
+};