From beb979b423ffca4eb63aa3ce2de22f9b13d74d4f Mon Sep 17 00:00:00 2001
From: "Jay Freeman (saurik)" <saurik@saurik.com>
Date: Sat, 9 Jan 2016 19:50:48 -0800
Subject: [PATCH 1/1] Add ?. syntax, for the object query documentation.

---
 Output.cpp     |  8 ++++++++
 Parser.ypp.in  |  7 +++++++
 Replace.cpp    | 17 +++++++++++++++++
 Scanner.lpp.in |  1 +
 Syntax.hpp     | 14 ++++++++++++++
 5 files changed, 47 insertions(+)

diff --git a/Output.cpp b/Output.cpp
index 50cc836..26e49fe 100644
--- a/Output.cpp
+++ b/Output.cpp
@@ -302,6 +302,14 @@ void CYAssignment::Output(CYOutput &out, CYFlags flags) const {
     rhs_->Output(out, Precedence(), CYRight(flags));
 }
 
+void CYAttemptMember::Output(CYOutput &out, CYFlags flags) const {
+    object_->Output(out, Precedence(), CYLeft(flags) | CYNoInteger);
+    if (const char *word = property_->Word())
+        out << "?." << word;
+    else
+        _assert(false);
+}
+
 void CYBlock::Output(CYOutput &out, CYFlags flags) const {
     out << '{' << '\n';
     ++out.indent_;
diff --git a/Parser.ypp.in b/Parser.ypp.in
index 6e889fa..3dbca89 100644
--- a/Parser.ypp.in
+++ b/Parser.ypp.in
@@ -305,6 +305,7 @@ type; })
 %token Plus "+"
 %token PlusEqual "+="
 %token PlusPlus "++"
+%token QuestionPeriod "?."
 %token Right ">"
 %token RightEqual ">="
 %token RightRight ">>"
@@ -2711,6 +2712,12 @@ MemberAccess
     : "." "[" AssignmentExpression[property] "]" { $$ = CYNew CYSubscriptMember(NULL, $property); }
     ;
 /* }}} */
+/* JavaScript FTW: Undefined Monad {{{ */
+MemberAccess
+    : "?." IdentifierName[property] { $$ = CYNew CYAttemptMember(NULL, CYNew CYString($property)); }
+    | "?." AutoComplete { driver.mode_ = CYDriver::AutoDirect; YYACCEPT; }
+    ;
+/* }}} */
 
 /* JavaScript FTW: Java "Anonymous Inner Classes" {{{ */
 BracedParameter
diff --git a/Replace.cpp b/Replace.cpp
index 68beb4f..d499dbc 100644
--- a/Replace.cpp
+++ b/Replace.cpp
@@ -125,6 +125,14 @@ CYExpression *CYAssignment::Replace(CYContext &context) {
     return this;
 }
 
+CYTarget *CYAttemptMember::Replace(CYContext &context) {
+    CYIdentifier *value(context.Unique());
+
+    return $C1($F(NULL, $P1($B(value)), $$
+        ->* $ CYReturn($ CYCondition($V(value), $M($V(value), property_), $V(value)))
+    ), object_);
+}
+
 CYStatement *CYBlock::Return() {
     CYImplicitReturn(code_);
     return this;
@@ -145,6 +153,15 @@ CYStatement *CYBreak::Replace(CYContext &context) {
 }
 
 CYTarget *CYCall::Replace(CYContext &context) {
+    // XXX: this also is a horrible hack but I'm still a month over schedule :(
+    if (CYAttemptMember *member = dynamic_cast<CYAttemptMember *>(function_)) {
+        CYIdentifier *value(context.Unique());
+
+        return $C1($F(NULL, $P1($B(value)), $$
+            ->* $ CYReturn($ CYCondition($V(value), $C($M($V(value), member->property_), arguments_), $V(value)))
+        ), member->object_);
+    }
+
     context.Replace(function_);
     arguments_->Replace(context);
     return this;
diff --git a/Scanner.lpp.in b/Scanner.lpp.in
index e16900a..dc8a3dd 100644
--- a/Scanner.lpp.in
+++ b/Scanner.lpp.in
@@ -370,6 +370,7 @@ XMLName {XMLNameStart}{XMLNamePart}*
 "%"    L F(tk::Percent, hi::Operator);
 "%="   L F(tk::PercentEqual, hi::Operator);
 "."    L F(tk::Period, hi::Operator);
+"?."   L F(tk::QuestionPeriod, hi::Operator);
 "|"    L F(tk::Pipe, hi::Operator);
 "|="   L F(tk::PipeEqual, hi::Operator);
 "||"   L F(tk::PipePipe, hi::Operator);
diff --git a/Syntax.hpp b/Syntax.hpp
index c710d89..4b25b30 100644
--- a/Syntax.hpp
+++ b/Syntax.hpp
@@ -1481,6 +1481,20 @@ struct CYDirectMember :
     virtual void Output(CYOutput &out, CYFlags flags) const;
 };
 
+struct CYAttemptMember :
+    CYMember
+{
+    CYAttemptMember(CYExpression *object, CYExpression *property) :
+        CYMember(object, property)
+    {
+    }
+
+    CYPrecedence(1)
+
+    virtual CYTarget *Replace(CYContext &context);
+    virtual void Output(CYOutput &out, CYFlags flags) const;
+};
+
 struct CYIndirectMember :
     CYMember
 {
-- 
2.45.2