What are the functions used to create the nodes of syntax tree?

In programming languages, the functions used to create the nodes of a syntax tree are typically called constructors. Here are the steps to create nodes of a syntax tree:

1. Define the Node Structure: The first step is to define the structure of a node. This usually includes the type of the node (like 'expression', 'statement', 'identifier', etc.), the value of the node (if any), and references to child nodes.

2. Create Constructor Functions: For each type of node, you would typically create a constructor function. This function takes the necessary parameters to create a node of its type. For example, an 'identifier' node might require a 'name' parameter, while an 'expression' node might require 'operator', 'left', and 'right' parameters (representing the left and right operands of the expression).

3. Use the Constructor Functions: When you parse the source code and build the syntax tree, you use these constructor functions to create nodes. For example, when you encounter an identifier in the source code, you would call the 'identifier' constructor function with the name of the identifier to create a new 'identifier' node.

4. Link the Nodes: As you create nodes, you also link them together to form the tree structure. For example, if you parse an expression that includes an identifier, you would first create an 'identifier' node for the identifier, then create an 'expression' node for the expression, and set the 'identifier' node as one of the child nodes of the 'expression' node.

5. Return the Root Node: Finally, after you've parsed the entire source code and built the syntax tree, you return the root node of the tree. This node represents the entire program and has all other nodes as its descendants.