Implement support for bash & completion flow generation

extras/scripts/completion/bash.py

@@ -0,0 +1,83 @@
+from enum import Enum
+from functools import singledispatch
+
+from completion_flow import (
+    And,
+    Check,
+    Condition,
+    If,
+    Node,
+    Not,
+    Suggest,
+    Suggestion,
+    Variable,
+    generate_flow,
+)
+
+
+class BashVariable(str, Enum):
+    CURRENT = 'COMP_CWORD'
+    NORMARG = 'NORMARG'
+    CURRENT_WORD = 'cur_word'
+    PREDECESSOR = 'prev_word'
+    METHODS = 'METHODS'
+
+
+SUGGESTION_TO_FUNCTION = {
+    Suggestion.METHOD: '_http_complete_methods',
+    Suggestion.URL: '_http_complete_url',
+    Suggestion.REQUEST_ITEM: '_httpie_complete_request_item',
+}
+
+
+@singledispatch
+def compile_bash(node: Node) -> ...:
+    raise NotImplementedError(f'{type(node)} is not supported')
+
+
+@compile_bash.register(If)
+def compile_if(node: If) -> str:
+    check = compile_bash(node.check)
+    action = compile_bash(node.action)
+    return f'if {check}; then\n    {action}\nfi'
+
+
+@compile_bash.register(Check)
+def compile_check(node: Check) -> str:
+    args = [
+        BashVariable(arg.name) if isinstance(arg, Variable) else arg
+        for arg in node.args
+    ]
+
+    if node.condition is Condition.POSITION_EQ:
+        return f'(( {BashVariable.CURRENT} == {BashVariable.NORMARG} + {args[0]} ))'
+    elif node.condition is Condition.POSITION_GE:
+        return f'(( {BashVariable.CURRENT} >= {BashVariable.NORMARG} + {args[0]} ))'
+    elif node.condition is Condition.CONTAINS_PREDECESSOR:
+        parts = [
+            '[[ ',
+            '" ${',
+            BashVariable.METHODS,
+            '[*]} " =~ " ${',
+            BashVariable.PREDECESSOR,
+            '} " ]]',
+        ]
+        return ''.join(parts)
+
+
+@compile_bash.register(And)
+def compile_and(node: And) -> str:
+    return ' && '.join(compile_bash(check) for check in node.checks)
+
+
+@compile_bash.register(Not)
+def compile_not(node: Not) -> str:
+    return f'! {compile_bash(node.check)}'
+
+
+@compile_bash.register(Suggest)
+def compile_suggest(node: Suggest) -> str:
+    return (
+        SUGGESTION_TO_FUNCTION[node.suggestion]
+        + f' "${BashVariable.CURRENT_WORD}"'
+    )