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LeMP Reference: Built-in macros

Note: The # character in macro names has two meanings. Usually it means “this macro produces no direct output and will disappear from the output file.” The other meaning is “this is one of the global macros that is always available and cannot be un-imported.”

Scoped Properties

Some of these macros refer to “scoped properties” which is actually the IMacroContext.ScopedProperties collection that all macros have access to. When one macro changes a scoped property, the changes are visible to other macros that are processed later (i.e. later statements, or later parts of an expression). However, they are scoped, meaning that any changes you make to them are not visible outside the current braced block. Conceptually, a closing brace “reverts” any changes that were made inside the braces.

Scoped properties whose key is a Symbol that starts with # are reserved for use by built-in macros and standard macros.

By default, there are two globally-scoped properties, #inputFileName and #inputFolder. It is possible to create additional globally-scoped properties with the --set and --snippet command-line options (e.g. --set:#haveContractRewriter=true or --snippet:#assertMethodForRequires=Contract.Requires).

Global macros (always available)

#importMacros

#importMacros(namespace);
import_macros(namespace); // alias for #importMacros
import_macros namespace;  // LES only

LeMP will look for macros in the specified namespace. Only applies within the current braced block. Note: normal C# using statements can also cause macros to be imported.

#unimportMacros

#unimportMacros(namespace1, namespace2)

Tells LeMP to stop looking for macros in the specified namespace(s). Only applies within the current braced block.

#noLexicalMacros

#noLexicalMacros(expr);

Suppresses macro invocations inside the specified expression. The word #noLexicalMacros is removed from the output.

#setScopedProperty

#setScopedProperty(keyLiteral, valueLiteral);

Sets the value of a scoped property, using the first parameter (usually a @@symbol) as a key in the property dictionary. The key and value must both be literals; expressions are not supported.

Note: Usually #set is used instead.

#setScopedPropertyQuote

#setScopedPropertyQuote(keyLiteral, valueCode);

Sets the value of a scoped property to an LNode, using the first parameter (usually a @@symbol) as a key in the property dictionary. The key must be a literal, while the value can be any expression.

Note: Usually #snippet is used instead.

#getScopedProperty

#getScopedProperty(keyLiteral, defaultCode);

Replaces the current node with the value of a scoped property. The key must be a literal or an identifier. If the key is an identifier, it is treated as a symbol instead, e.g. KEY is equivalent to @@KEY. If the scoped property is an LNode, the code it represents is expanded in-place. If the scoped property is anything else, its value is inserted as a literal. If the property does not exist, the second parameter is used instead. The second parameter is optional; if there is no second parameter and the requested property does not exist, an error is printed.

Note: Usually #get is used instead.

Other built-in macros (LeMP.Prelude namespace)

noMacro

noMacro(Code)

Pass code through to the output language, without macro processing.

#get

#get(key, defaultValueOpt)

Alias for #getScopedProperty. Gets a literal or code snippet that was previously set in this scope. If the key is an identifier, it is treated as a symbol instead, e.g. #get(Foo) is equivalent to #get(@@Foo).

import_macros

import_macros Namespace

Use macros from specified namespace. The ‘macros’ modifier imports macros only, deleting this statement from the output.

printKnownMacros

printKnownMacros;

Prints a table of all macros known to LeMP, as (invalid) C# code.

#set and #snippet

#set Identifier = literalValue; 
#set Identifier;  // the default literal value is true
#snippet Identifier = expression;
#snippet Identifier = { statement(s); }; 

Sets an option, or saves a snippet of code for use later. #set is a synonym for #setScopedProperty, while #snippet is a synonym for #setScopedPropertyQuote. #get can be used to get the saved value or code snippet, but #set and #snippet are most often used to set options recognized by other macros. For example,

import_macros

import_macros Namespace; // LES syntax
import_macros(Namespace); // EC# syntax

Use macros from specified namespace.

printKnownMacros

printKnownMacros;

Prints a table of all macros known to LeMP, including macros that have not been imported. The output is not valid C# code.