update READMEs

vyper/ast/README.md

@@ -12,8 +12,6 @@ and parsing NatSpec docstrings.
 
 * [`annotation.py`](annotation.py): Contains the `AnnotatingVisitor` class, used to
 annotate and modify the Python AST prior to converting it to a Vyper AST.
-* [`folding.py`](folding.py): Functions for evaluating and replacing literal
-nodes within the Vyper AST.
 * [`natspec.py`](natspec.py): Functions for parsing NatSpec docstrings within the
 source.
 * [`nodes.py`](nodes.py): Contains the Vyper node classes, and the `get_node`
@@ -70,24 +68,6 @@ or parents that match a desired pattern.
 To learn more about these methods, read their docstrings in the `VyperNode` class
 in [`nodes.py`](nodes.py).
 
-### Modifying the AST
-
-[`folding.py`](folding.py) contains the `fold` function, a high-level method called
-to evaluating and replacing literal nodes within the AST. Some examples of literal
-folding include:
-
-* arithmetic operations (`3+2` becomes `5`)
-* references to literal arrays (`["foo", "bar"][1]` becomes `"bar"`)
-* builtin functions applied to literals (`min(1,2)` becomes `1`)
-
-The process of literal folding includes:
-
-1. Foldable node classes are evaluated via their `fold` method, which attempts to create a new `Constant` from the content of the given node.
-2. Replacement nodes are generated using the `from_node` class method within the new
-node class.
-3. The modification of the tree is handled by `Module.replace_in_tree`, which locates
-the existing node and replaces it with a new one.
-
 ## Design
 
 ### `__slots__`

vyper/compiler/README.md

@@ -25,8 +25,6 @@ The compilation process includes the following broad phases:
 
 1. In [`vyper.ast`](../ast), the source code is parsed and converted to an
 abstract syntax tree.
-1. In [`vyper.ast.folding`](../ast/folding.py), literal Vyper AST nodes are
-evaluated and replaced with the resulting values.
 1. The [`GlobalContext`](../codegen/global_context.py) object is generated from the
 Vyper AST, analyzing and organizing the nodes prior to IR generation.
 1. In [`vyper.codegen.module`](../codegen/module.py), the contextualized nodes are

vyper/semantics/README.md

@@ -25,6 +25,7 @@ Vyper abstract syntax tree (AST).
   * [`data_positions`](analysis/data_positions.py): Functions for tracking storage variables and allocating storage slots
   * [`levenhtein_utils.py`](analysis/levenshtein_utils.py): Helper for better error messages
   * [`local.py`](analysis/local.py): Validates the local namespace of each function within a contract
+  * [`pre_typecheck.py`](analysis/pre_typecheck.py): Evaluate foldable nodes and populate their metadata with the replacement nodes.
   * [`module.py`](analysis/module.py): Validates the module namespace of a contract.
   * [`utils.py`](analysis/utils.py): Functions for comparing and validating types
 * [`data_locations.py`](data_locations.py): `DataLocation` object for type location information
@@ -35,13 +36,23 @@ Vyper abstract syntax tree (AST).
 
 The [`analysis`](analysis) subpackage contains the top-level `validate_semantics`
 function. This function is used to verify and type-check a contract. The process
-consists of three steps:
+consists of four steps:
 
-1. Preparing the builtin namespace
-2. Validating the module-level scope
-3. Annotating and validating local scopes
+1. Populating the metadata of foldable nodes with their replacement nodes
+2. Preparing the builtin namespace
+3. Validating the module-level scope
+4. Annotating and validating local scopes
 
-### 1. Preparing the builtin namespace
+### 1. Populating the metadata of foldable nodes with their replacement nodes
+
+[`analysis/pre_typecheck.py`](analysis/pre_typecheck.py) populates the metadata of foldable nodes with their replacement nodes.
+
+This process includes:
+1. Foldable node classes and builtin functions are evaluated via their `fold` method, which attempts to create a new `Constant` from the content of the given node.
+2. Replacement nodes are generated using the `from_node` class method within the new
+node class.
+
+### 2. Preparing the builtin namespace
 
 The [`Namespace`](namespace.py) object represents the namespace for a contract.
 Builtins are added upon initialization of the object. This includes:
@@ -51,19 +62,19 @@ Builtins are added upon initialization of the object. This includes:
 * Adding builtin functions from the [`functions`](../builtins/functions.py) package
 * Adding / resetting `self` and `log`
 
-### 2. Validating the Module Scope
+### 3. Validating the Module Scope
 
-[`validation/module.py`](validation/module.py) validates the module-level scope
+[`analysis/module.py`](analysis/module.py) validates the module-level scope
 of a contract. This includes:
 
 * Generating user-defined types (e.g. structs and interfaces)
 * Creating type definitions for storage variables, user-defined constants, events
 and functions
 * Validating import statements and function signatures
 
-### 3. Annotating and validating the Local Scopes
+### 4. Annotating and validating the Local Scopes
 
-[`validation/local.py`](validation/local.py) validates the local scope within each
+[`analysis/local.py`](analysis/local.py) validates the local scope within each
 function in a contract. `FunctionNodeVisitor` is used to iterate over the statement
 nodes in each function body, annotate them and apply appropriate checks.