ast: Add AST JSON printer

5 files changed, 174 insertions, 12 deletions

diff --git a/mesonbuild/ast/__init__.py b/mesonbuild/ast/__init__.py
index 48de5231a..4fb56cb86 100644
--- a/mesonbuild/ast/__init__.py
+++ b/mesonbuild/ast/__init__.py
@@ -20,6 +20,7 @@ __all__ = [
     'AstInterpreter',
     'AstIDGenerator',
     'AstIndentationGenerator',
+    'AstJSONPrinter',
     'AstVisitor',
     'AstPrinter',
     'IntrospectionInterpreter',
@@ -30,4 +31,4 @@ from .interpreter import AstInterpreter
 from .introspection import IntrospectionInterpreter, build_target_functions
 from .visitor import AstVisitor
 from .postprocess import AstConditionLevel, AstIDGenerator, AstIndentationGenerator
-from .printer import AstPrinter
+from .printer import AstPrinter, AstJSONPrinter
diff --git a/mesonbuild/ast/printer.py b/mesonbuild/ast/printer.py
index 39e2ccae4..a57ba20d3 100644
--- a/mesonbuild/ast/printer.py
+++ b/mesonbuild/ast/printer.py
@@ -18,6 +18,7 @@
 from .. import mparser
 from . import AstVisitor
 import re
+import typing as T
 
 arithmic_map = {
     'add': '+',
@@ -155,7 +156,7 @@ class AstPrinter(AstVisitor):
             self.append_padded(prefix + 'if', node)
             prefix = 'el'
             i.accept(self)
-        if node.elseblock:
+        if not isinstance(node.elseblock, mparser.EmptyNode):
             self.append('else', node)
             node.elseblock.accept(self)
         self.append('endif', node)
@@ -199,3 +200,160 @@ class AstPrinter(AstVisitor):
             self.result = re.sub(r', \n$', '\n', self.result)
         else:
             self.result = re.sub(r', $', '', self.result)
+
+class AstJSONPrinter(AstVisitor):
+    def __init__(self) -> None:
+        self.result = {}  # type: T.Dict[str, T.Any]
+        self.current = self.result
+
+    def _accept(self, key: str, node: mparser.BaseNode) -> None:
+        old = self.current
+        data = {}  # type: T.Dict[str, T.Any]
+        self.current = data
+        node.accept(self)
+        self.current = old
+        self.current[key] = data
+
+    def _accept_list(self, key: str, nodes: T.Sequence[mparser.BaseNode]) -> None:
+        old = self.current
+        datalist = []  # type: T.List[T.Dict[str, T.Any]]
+        for i in nodes:
+            self.current = {}
+            i.accept(self)
+            datalist += [self.current]
+        self.current = old
+        self.current[key] = datalist
+
+    def _raw_accept(self, node: mparser.BaseNode, data: T.Dict[str, T.Any]) -> None:
+        old = self.current
+        self.current = data
+        node.accept(self)
+        self.current = old
+
+    def setbase(self, node: mparser.BaseNode) -> None:
+        self.current['node'] = type(node).__name__
+        self.current['lineno'] = node.lineno
+        self.current['colno'] = node.colno
+        self.current['end_lineno'] = node.end_lineno
+        self.current['end_colno'] = node.end_colno
+
+    def visit_default_func(self, node: mparser.BaseNode) -> None:
+        self.setbase(node)
+
+    def gen_ElementaryNode(self, node: mparser.ElementaryNode) -> None:
+        self.current['value'] = node.value
+        self.setbase(node)
+
+    def visit_BooleanNode(self, node: mparser.BooleanNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_IdNode(self, node: mparser.IdNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_NumberNode(self, node: mparser.NumberNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_StringNode(self, node: mparser.StringNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_ArrayNode(self, node: mparser.ArrayNode) -> None:
+        self._accept('args', node.args)
+        self.setbase(node)
+
+    def visit_DictNode(self, node: mparser.DictNode) -> None:
+        self._accept('args', node.args)
+        self.setbase(node)
+
+    def visit_OrNode(self, node: mparser.OrNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.setbase(node)
+
+    def visit_AndNode(self, node: mparser.AndNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.setbase(node)
+
+    def visit_ComparisonNode(self, node: mparser.ComparisonNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.current['ctype'] = node.ctype
+        self.setbase(node)
+
+    def visit_ArithmeticNode(self, node: mparser.ArithmeticNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.current['op'] = arithmic_map[node.operation]
+        self.setbase(node)
+
+    def visit_NotNode(self, node: mparser.NotNode) -> None:
+        self._accept('right', node.value)
+        self.setbase(node)
+
+    def visit_CodeBlockNode(self, node: mparser.CodeBlockNode) -> None:
+        self._accept_list('lines', node.lines)
+        self.setbase(node)
+
+    def visit_IndexNode(self, node: mparser.IndexNode) -> None:
+        self._accept('object', node.iobject)
+        self._accept('index', node.index)
+        self.setbase(node)
+
+    def visit_MethodNode(self, node: mparser.MethodNode) -> None:
+        self._accept('object', node.source_object)
+        self._accept('args', node.args)
+        self.current['name'] = node.name
+        self.setbase(node)
+
+    def visit_FunctionNode(self, node: mparser.FunctionNode) -> None:
+        self._accept('args', node.args)
+        self.current['name'] = node.func_name
+        self.setbase(node)
+
+    def visit_AssignmentNode(self, node: mparser.AssignmentNode) -> None:
+        self._accept('value', node.value)
+        self.current['var_name'] = node.var_name
+        self.setbase(node)
+
+    def visit_PlusAssignmentNode(self, node: mparser.PlusAssignmentNode) -> None:
+        self._accept('value', node.value)
+        self.current['var_name'] = node.var_name
+        self.setbase(node)
+
+    def visit_ForeachClauseNode(self, node: mparser.ForeachClauseNode) -> None:
+        self._accept('items', node.items)
+        self._accept('block', node.block)
+        self.current['varnames'] = node.varnames
+        self.setbase(node)
+
+    def visit_IfClauseNode(self, node: mparser.IfClauseNode) -> None:
+        self._accept_list('ifs', node.ifs)
+        self._accept('else', node.elseblock)
+        self.setbase(node)
+
+    def visit_UMinusNode(self, node: mparser.UMinusNode) -> None:
+        self._accept('right', node.value)
+        self.setbase(node)
+
+    def visit_IfNode(self, node: mparser.IfNode) -> None:
+        self._accept('condition', node.condition)
+        self._accept('block', node.block)
+        self.setbase(node)
+
+    def visit_TernaryNode(self, node: mparser.TernaryNode) -> None:
+        self._accept('condition', node.condition)
+        self._accept('true', node.trueblock)
+        self._accept('false', node.falseblock)
+        self.setbase(node)
+
+    def visit_ArgumentNode(self, node: mparser.ArgumentNode) -> None:
+        self._accept_list('positional', node.arguments)
+        kwargs_list = []  # type: T.List[T.Dict[str, T.Dict[str, T.Any]]]
+        for key, val in node.kwargs.items():
+            key_res = {}  # type: T.Dict[str, T.Any]
+            val_res = {}  # type: T.Dict[str, T.Any]
+            self._raw_accept(key, key_res)
+            self._raw_accept(val, val_res)
+            kwargs_list += [{'key': key_res, 'val': val_res}]
+        self.current['kwargs'] = kwargs_list
+        self.setbase(node)
diff --git a/mesonbuild/ast/visitor.py b/mesonbuild/ast/visitor.py
index 37be4632a..451020d2d 100644
--- a/mesonbuild/ast/visitor.py
+++ b/mesonbuild/ast/visitor.py
@@ -113,8 +113,7 @@ class AstVisitor:
         self.visit_default_func(node)
         for i in node.ifs:
             i.accept(self)
-        if node.elseblock:
-            node.elseblock.accept(self)
+        node.elseblock.accept(self)
 
     def visit_UMinusNode(self, node: mparser.UMinusNode) -> None:
         self.visit_default_func(node)
diff --git a/mesonbuild/mintro.py b/mesonbuild/mintro.py
index 54e302bc7..8eb659b6e 100644
--- a/mesonbuild/mintro.py
+++ b/mesonbuild/mintro.py
@@ -22,7 +22,7 @@ project files and don't need this info."""
 import json
 from . import build, coredata as cdata
 from . import mesonlib
-from .ast import IntrospectionInterpreter, build_target_functions, AstConditionLevel, AstIDGenerator, AstIndentationGenerator
+from .ast import IntrospectionInterpreter, build_target_functions, AstConditionLevel, AstIDGenerator, AstIndentationGenerator, AstJSONPrinter
 from . import mlog
 from .backend import backends
 from .mparser import BaseNode, FunctionNode, ArrayNode, ArgumentNode, StringNode
@@ -62,6 +62,7 @@ def get_meson_introspection_types(coredata: T.Optional[cdata.CoreData] = None,
         benchmarkdata = testdata = installdata = None
 
     return {
+        'ast': IntroCommand('Dump the AST of the meson file', no_bd=dump_ast),
         'benchmarks': IntroCommand('List all benchmarks', func=lambda: list_benchmarks(benchmarkdata)),
         'buildoptions': IntroCommand('List all build options', func=lambda: list_buildoptions(coredata), no_bd=list_buildoptions_from_source),
         'buildsystem_files': IntroCommand('List files that make up the build system', func=lambda: list_buildsystem_files(builddata, interpreter)),
@@ -89,6 +90,11 @@ def add_arguments(parser):
                         help='Always use the new JSON format for multiple entries (even for 0 and 1 introspection commands)')
     parser.add_argument('builddir', nargs='?', default='.', help='The build directory')
 
+def dump_ast(intr: IntrospectionInterpreter) -> T.Dict[str, T.Any]:
+    printer = AstJSONPrinter()
+    intr.ast.accept(printer)
+    return printer.result
+
 def list_installed(installdata):
     res = {}
     if installdata is not None:
diff --git a/mesonbuild/mparser.py b/mesonbuild/mparser.py
index 2cffc4718..b9e381e98 100644
--- a/mesonbuild/mparser.py
+++ b/mesonbuild/mparser.py
@@ -426,8 +426,8 @@ class IfNode(BaseNode):
 class IfClauseNode(BaseNode):
     def __init__(self, linenode: BaseNode):
         super().__init__(linenode.lineno, linenode.colno, linenode.filename)
-        self.ifs = []  # type: T.List[IfNode]
-        self.elseblock = EmptyNode(linenode.lineno, linenode.colno, linenode.filename)  # type: T.Union[EmptyNode, CodeBlockNode]
+        self.ifs = []          # type: T.List[IfNode]
+        self.elseblock = None  # type: T.Union[EmptyNode, CodeBlockNode]
 
 class UMinusNode(BaseNode):
     def __init__(self, current_location: Token, value: BaseNode):
@@ -747,9 +747,7 @@ class Parser:
         block = self.codeblock()
         clause.ifs.append(IfNode(clause, condition, block))
         self.elseifblock(clause)
-        elseblock = self.elseblock()
-        if elseblock:
-            clause.elseblock = elseblock
+        clause.elseblock = self.elseblock()
         return clause
 
     def elseifblock(self, clause) -> None:
@@ -759,11 +757,11 @@ class Parser:
             b = self.codeblock()
             clause.ifs.append(IfNode(s, s, b))
 
-    def elseblock(self) -> T.Optional[CodeBlockNode]:
+    def elseblock(self) -> T.Union[CodeBlockNode, EmptyNode]:
         if self.accept('else'):
             self.expect('eol')
             return self.codeblock()
-        return None
+        return EmptyNode(self.current.lineno, self.current.colno, self.current.filename)
 
     def line(self) -> BaseNode:
         block_start = self.current