Shell: Add support for 'immediate' expressions as variable substitutions

This commit adds a few basic variable substitution operations:
- length
    Find the length of a string or a list
- length_across
    Find the lengths of things inside a list
- remove_{suffix,prefix}
    Remove a suffix or a prefix from all the passed values
- regex_replace
    Replace all matches of a given regex with a given template
- split
    Split the given string with the given delimiter (or to its
    code points if the delimiter is empty)
- concat_lists
    concatenates any given lists into one

Closes #4316 (the ancient version of this same feature)

1 files changed, 2 insertions, 0 deletions

diff --git a/Userland/Shell/NodeVisitor.h b/Userland/Shell/NodeVisitor.h
index e252ec4ebd..6d45bc3ab1 100644
--- a/Userland/Shell/NodeVisitor.h
+++ b/Userland/Shell/NodeVisitor.h
@@ -53,6 +53,7 @@ public:
     virtual void visit(const AST::HistoryEvent*);
     virtual void visit(const AST::Execute*);
     virtual void visit(const AST::IfCond*);
+    virtual void visit(const AST::ImmediateExpression*);
     virtual void visit(const AST::Join*);
     virtual void visit(const AST::MatchExpr*);
     virtual void visit(const AST::Or*);
@@ -68,6 +69,7 @@ public:
     virtual void visit(const AST::StringLiteral*);
     virtual void visit(const AST::StringPartCompose*);
     virtual void visit(const AST::SyntaxError*);
+    virtual void visit(const AST::SyntheticNode*);
     virtual void visit(const AST::Tilde*);
     virtual void visit(const AST::VariableDeclarations*);
     virtual void visit(const AST::WriteAppendRedirection*);