lsp explain and index

explain.cm

@@ -0,0 +1,235 @@
+// explain.cm — Query module over a semantic index.
+//
+// Usage:
+//   var explain = use('explain').make(index)
+//   explain.at_span(line, col)
+//   explain.by_symbol(name)
+//   explain.call_chain(symbol_id, depth)
+
+// Check if a position (line, col) falls inside a span.
+var span_contains = function(span, line, col) {
+  if (line < span.from_row || line > span.to_row) return false
+  if (line == span.from_row && col < span.from_col) return false
+  if (line == span.to_row && col > span.to_col) return false
+  return true
+}
+
+// Create an explain interface bound to a single file index.
+var make = function(index) {
+
+  // Find symbol or reference at a given line/col position.
+  var at_span = function(line, col) {
+    var _i = 0
+    var sym = null
+    var ref = null
+    var found_sym = null
+    var found_ref = null
+    var result_refs = []
+    var result_calls = []
+
+    // Search symbols for one whose decl_span contains (line, col).
+    _i = 0
+    while (_i < length(index.symbols)) {
+      sym = index.symbols[_i]
+      if (sym.decl_span != null && span_contains(sym.decl_span, line, col)) {
+        found_sym = sym
+        break
+      }
+      _i = _i + 1
+    }
+
+    // If no symbol found, search references.
+    if (found_sym == null) {
+      _i = 0
+      while (_i < length(index.references)) {
+        ref = index.references[_i]
+        if (ref.span != null && span_contains(ref.span, line, col)) {
+          found_ref = ref
+          // Look up the symbol this reference points to.
+          if (ref.symbol_id != null) {
+            _i = 0
+            while (_i < length(index.symbols)) {
+              if (index.symbols[_i].symbol_id == ref.symbol_id) {
+                found_sym = index.symbols[_i]
+                break
+              }
+              _i = _i + 1
+            }
+          }
+          break
+        }
+        _i = _i + 1
+      }
+    }
+
+    if (found_sym == null && found_ref == null) return null
+
+    // Gather all references to this symbol.
+    if (found_sym != null && index.reverse_refs[found_sym.name] != null) {
+      result_refs = index.reverse_refs[found_sym.name]
+    }
+
+    // Gather call sites.
+    _i = 0
+    while (_i < length(index.call_sites)) {
+      if (found_sym != null && index.call_sites[_i].callee_symbol_id == found_sym.symbol_id) {
+        result_calls[] = index.call_sites[_i]
+      }
+      _i = _i + 1
+    }
+
+    return {
+      symbol: found_sym,
+      reference: found_ref,
+      references: result_refs,
+      call_sites: result_calls,
+      imports: index.imports
+    }
+  }
+
+  // Find all symbols matching a name.
+  var by_symbol = function(name) {
+    var _i = 0
+    var matches = []
+    var result_refs = []
+    var result_calls = []
+
+    // Find matching symbols.
+    _i = 0
+    while (_i < length(index.symbols)) {
+      if (index.symbols[_i].name == name) {
+        matches[] = index.symbols[_i]
+      }
+      _i = _i + 1
+    }
+
+    // Gather all references to this name.
+    if (index.reverse_refs[name] != null) {
+      result_refs = index.reverse_refs[name]
+    }
+
+    // Gather call sites where this name is the callee.
+    _i = 0
+    while (_i < length(index.call_sites)) {
+      if (index.call_sites[_i].callee == name) {
+        result_calls[] = index.call_sites[_i]
+      }
+      _i = _i + 1
+    }
+
+    return {
+      symbols: matches,
+      references: result_refs,
+      call_sites: result_calls
+    }
+  }
+
+  // Build a call chain from/to a symbol.
+  var call_chain = function(symbol_id, depth) {
+    var max_depth = (depth != null) ? depth : 2
+    var callers = []
+    var callees = []
+    var _i = 0
+    var cs = null
+
+    // Callees: calls made FROM this symbol.
+    _i = 0
+    while (_i < length(index.call_sites)) {
+      cs = index.call_sites[_i]
+      if (cs.enclosing == symbol_id) {
+        callees[] = {
+          callee: cs.callee,
+          callee_symbol_id: cs.callee_symbol_id,
+          span: cs.span,
+          args_count: cs.args_count
+        }
+      }
+      _i = _i + 1
+    }
+
+    // Callers: calls TO this symbol.
+    _i = 0
+    while (_i < length(index.call_sites)) {
+      cs = index.call_sites[_i]
+      if (cs.callee_symbol_id == symbol_id) {
+        callers[] = {
+          from: cs.enclosing,
+          span: cs.span,
+          args_count: cs.args_count
+        }
+      }
+      _i = _i + 1
+    }
+
+    return {
+      symbol_id: symbol_id,
+      callers: callers,
+      callees: callees,
+      depth: max_depth
+    }
+  }
+
+  return {
+    at_span: at_span,
+    by_symbol: by_symbol,
+    call_chain: call_chain
+  }
+}
+
+// Search across multiple file indexes.
+var explain_across = function(indexes, name) {
+  var _i = 0
+  var _j = 0
+  var all_symbols = []
+  var all_refs = []
+  var all_calls = []
+  var idx = null
+  var refs = null
+
+  _i = 0
+  while (_i < length(indexes)) {
+    idx = indexes[_i]
+
+    // Gather symbols.
+    _j = 0
+    while (_j < length(idx.symbols)) {
+      if (idx.symbols[_j].name == name) {
+        all_symbols[] = idx.symbols[_j]
+      }
+      _j = _j + 1
+    }
+
+    // Gather references.
+    refs = idx.reverse_refs[name]
+    if (refs != null) {
+      _j = 0
+      while (_j < length(refs)) {
+        all_refs[] = refs[_j]
+        _j = _j + 1
+      }
+    }
+
+    // Gather call sites.
+    _j = 0
+    while (_j < length(idx.call_sites)) {
+      if (idx.call_sites[_j].callee == name) {
+        all_calls[] = idx.call_sites[_j]
+      }
+      _j = _j + 1
+    }
+
+    _i = _i + 1
+  }
+
+  return {
+    symbols: all_symbols,
+    references: all_refs,
+    call_sites: all_calls
+  }
+}
+
+return {
+  make: make,
+  explain_across: explain_across,
+  span_contains: span_contains
+}