From 10eec286fa89ce63fa5d8b6cf30d5fe90c4193e6 Mon Sep 17 00:00:00 2001
From: Celestino Amoroso <celestino.amoroso@gmail.com>
Date: Sat, 27 Apr 2024 06:12:30 +0200
Subject: [PATCH] new operator '111123' that returns the content of the current
 context or the context of an iterator

---
 operator-context.go | 49 +++++++++++++++++++++++++++++++++++++++++++++
 scanner.go          |  6 ++++--
 symbol.go           |  3 ++-
 3 files changed, 55 insertions(+), 3 deletions(-)
 create mode 100644 operator-context.go

diff --git a/operator-context.go b/operator-context.go
new file mode 100644
index 0000000..b4c0464
--- /dev/null
+++ b/operator-context.go
@@ -0,0 +1,49 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-context-value.go
+package expr
+
+//-------- context term
+
+func newContextTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 1),
+		position: posPrefix,
+		priority: priPrePost,
+		evalFunc: evalContextValue,
+	}
+}
+
+func evalContextValue(ctx ExprContext, self *term) (v any, err error) {
+	var childValue any
+
+	var sourceCtx ExprContext
+	if len(self.children) == 0 {
+		sourceCtx = ctx
+	} else if childValue, err = self.evalPrefix(ctx); err == nil {
+		if dc, ok := childValue.(*dataCursor); ok {
+			sourceCtx = dc.ctx
+		}
+	} else {
+		return
+	}
+
+	if sourceCtx != nil {
+		keys := sourceCtx.EnumVars(func(name string) bool { return name[0] != '_' })
+		d := make(map[string]any)
+		for _, key := range keys {
+			d[key], _ = sourceCtx.GetVar(key)
+		}
+		v = d
+	} else {
+		err = self.errIncompatibleType(childValue)
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymDoubleDollar, newContextTerm)
+}
diff --git a/scanner.go b/scanner.go
index dd5c200..8a6ba93 100644
--- a/scanner.go
+++ b/scanner.go
@@ -242,6 +242,8 @@ func (self *scanner) fetchNextToken() (tk *Token) {
 			if next, _ := self.peek(); next == '(' {
 				tk = self.moveOn(SymDollarRound, ch, next)
 				tk.source += ")"
+			} else if next == '$' {
+				tk = self.moveOn(SymDoubleDollar, ch, next)
 			} else {
 				tk = self.makeToken(SymDollar, ch)
 			}
@@ -249,8 +251,8 @@ func (self *scanner) fetchNextToken() (tk *Token) {
 			if next, _ := self.peek(); next == ')' {
 				tk = self.moveOn(SymOpenClosedRound, ch, next)
 			} else {
-			tk = self.makeToken(SymOpenRound, ch)
-		}
+				tk = self.makeToken(SymOpenRound, ch)
+			}
 		case ')':
 			tk = self.makeToken(SymClosedRound, ch)
 		case '[':
diff --git a/symbol.go b/symbol.go
index 5d4ea20..12132a0 100644
--- a/symbol.go
+++ b/symbol.go
@@ -63,7 +63,8 @@ const (
 	SymAppend                            //  52: '<<'
 	SymCaret                             //  53: '^'
 	SymDollarRound                       //  54: '$('
-	SymOpenClosedRound //  55: '()'
+	SymOpenClosedRound                   //  55: '()'
+	SymDoubleDollar                      //  56: '$$
 	SymChangeSign
 	SymUnchangeSign
 	SymIdentifier